5870 Bottleneck Investigation (CPU and/or Memory Bandwidth)

The 5870 is fast, that's for sure, but looking like and enhanced and doubled 4890 it should be much faster, and definitely shouldn't be beat by 4890CF across the board. The card has power, but obviously isn't able to use very well. The two main culprits are immature drivers and a possible bandwidth bottleneck. While we have to wait and see for drivers, anyone with a 5870 in hand can easily test if the memory system is at fault.

This is a call for anyone who has a 5870 right now, and if no one steps up to the plate I will when mine comes in. A good methodology would be dropping the core and memory frequencies in half while observing how the performance changes across various programs (especially those that the 5870 doesn't scale well in, like hawx) as core and memory are individually adjusted. Come on guys, lets get to it!

Bs!

I'd like to see a comparison between 4890 CF and a single 5870 in direct benchmarks on the same system. Didn't see any today in the reviews.

I'd imagine drivers would also have some to do with it. The 5870 should pretty much always be faster than a 4870x2.

So it will take month again until the drivers catch up ? *yawn*

Nobody should touch those latest and greatest until they run like they should - it would speed up this process by a fair margin... Reds and greens alike :rolleyes:

dont think there will be a bottleneck by the pcie

the 5870 compare to 4890 is botllenecked by its mem bandwidth in comparison... if only it was 512bit or 7-8ghz..
then it would in my opinion might bottleneck a pcie 2.0

but in high res games it practically kills the 4890..
this i guess is where the bandwidth doesnt play much role as to computing power

Quote:

---

Originally Posted by cstkl1

dont think there will be a bottleneck by the pcie

the 5870 compare to 4890 is botllenecked by its mem bandwidth in comparison... if only it was 512bit or 7-8ghz..
then it would in my opinion might bottleneck a pcie 2.0

but in high res games it practically kills the 4890..
this i guess is where the bandwidth doesnt play much role as to computing power

---

an min fps... it kills EVERYTHING at min fps :D

Quote:

---

the 5870 compare to 4890 is botllenecked by its mem bandwidth in comparison... if only it was 512bit or 7-8ghz..
then it would in my opinion might bottleneck a pcie 2.0

but in high res games it practically kills the 4890..
this i guess is where the bandwidth doesnt play much role as to computing power

---

I think thats partly the case, however from reading ~5 reviews so far, I think that is partly that and partly VRAM bound. looking at the benches, the only cards that are able to outperform it are (single or multi GPU) cards that have 1GB++. If I had the money to buy a 5870, I would wait and get one (or two ;) ) that had 2GB mem as I was assuming that would be the case.

Plus Im not sure how many places have used the 9.10 beta drivers that AMD released, in the few test bits I scanned, they used 9.8 I think.

Quote:

---

Originally Posted by mcmeat51

looking at the benches, the only cards that are able to outperform it are (single or multi GPU) cards that have 1GB++. If I had the money to buy a 5870, I would wait and get one (or two ;) ) that had 2GB mem as I was assuming that would be the case.

---

In multigpu cards, that 2GB is mostly just the same texture memory mirrored for each one, so it behaves more like a 1GB card, although it's possible there are some optimizations to reduce memory usage.

I've been told my card is shipping this morning, when I get it, if no one else has stepped up to the plate, I'll settle once and for all if the memory bandwidth is what's holding the card back.

Quote:

---

In multigpu cards, that 2GB is mostly just the same texture memory mirrored for each one, so it behaves more like a 1GB card, although it's possible there are some optimizations to reduce memory usage.

---

True however that seemes like a trend to me. what is the theoretical mem bus throughput of a 5870 and the gtx295?

Quote:

---

Originally Posted by mcmeat51

True however that seemes like a trend to me. what is the theoretical mem bus throughput of a 5870 and the gtx295?

---

Theoretical mem bus throughput in a dual GPU card (with AFR) it's the same case than memory occupation. It has twice the bandwidth, because it has one bus for each GPU, but chances are that most of the bandwidth of the second GPU is being used to send to the second GPU the same info that the first bus is sending to the first GPU, because both need the same data.

With Alternate Frame Rendering, you have to think as if you have two completely different cards, each one rendering half of the frames (indeed, that's exactly what you have), so you can use the 2nd card to render the next frame while the 1st one is rendering the current one, if the CPU has finished to process that next frame.

You can't compare theoretical specs of dual and single GPU solutions so easily.

Quote:

---

Originally Posted by mcmeat51

True however that seemes like a trend to me. what is the theoretical mem bus throughput of a 5870 and the gtx295?

---

AFAIK theoretically AFR on 295 means that you have 275 with same amount of SPs, TMUs, ROPs, VRAM but with 2x core, SPs, bandwith clocks and 1 additional frame input lag(or same input lag as one gtx275).

Quote:

---

Originally Posted by hurleybird

I've been told my card is shipping this morning, when I get it, if no one else has stepped up to the plate, I'll settle once and for all if the memory bandwidth is what's holding the card back.

---

take a couple of games and try them at three settings
(1. medium quality, lower res, noAA)
(2. high quality, 1080, 4xAA) and
(3. Insane-o maximum quality, 1920 or 2560 or Eyefinity range res, 8xAA, 16xAF)

Clock your memory from 800mhz to 1400+mhz in 100mhz or so increments, and record the data. Guru3d has a new GPU tool for overclocking and overvolting core/mem on 5800 cards. I would be interested to see your benchmarks. Another exciting bench coming out from a poster at ocforums.com is going to be 5870 crossfire tests ran extensively on a P55 vs. an X58 to test the 8x/8x vs. 16x/16x PCIE.

I am really interested to see how your memory performance benchmarks go. good luck, and thanks!
:clap:

Actually, the plan is to clock both the memory and the core down to about half. That way the compute/bandwidth ratio stays the same and it's much easier to increase one or the other. Then I'll have the core or the memory stay the same while I increase on or the other in increments of maybe 150MHz. If the card reacts substantially more favorably to either core or memory frequency, we'll know there's an imbalance in the design.

Hopefully I get mine in tommorow (express shipping), but I do live somewhat north...

That might work too, but I would try both ways just to replicate real world scenarios.

We'll just have to see how far my card overclocks. If I can't get the memory high enough I won't get very much data the other way. Good compromise might be to lower both clocks to 3/4 as opposed to half and go from there.

lots of talk, but barely anybody has a 5870 lol...
im really curious about this myself, 5870 SHOULD be much faster than a 4890 considering ati doubled everything except for mem bw, which is still improved notably over a 4890... so its really odd the perf is only 40% higher than a 4890 on average... it could be that the shader cores are less efficient now that dx11 is added?

w1zzard disabled some sps on his 5870 to simulate a 5850, it would be really cool if we could disable half the sps and connected rops and ideally tmus, to basically have a 5870 cut down to the same specs as a 4890 and we can do a clock for clock compare...

BS mate!

http://www.techpowerup.com/reviews/A...Scaling/4.html

Quote:

---

Originally Posted by db87

BS mate!

http://www.techpowerup.com/reviews/A...Scaling/4.html

---

This review is testing PCI-e lane link width. Hurleybird is testing memory bandwidth on the board by under/over clocking the memory frequency. :confused:

Quote:

---

Originally Posted by saaya

a 5870 cut down to the same specs as a 4890 and we can do a clock for clock compare...

---

that would be sweet.

What tests do you want guys?

I can run them for you now :)

BTW first and foremost bottleneck is triangle setup. Same speed per clock as in RV770!
Let's look for more :yepp:

Quote:

---

Originally Posted by Lightman

BTW first and foremost bottleneck is triangle setup. Same speed per clock as in RV770!

---

So G300 won't be much faster then gtx285 too?

Quote:

---

Originally Posted by Lightman

What tests do you want guys?
I can run them for you now :)

---

Bench a video game at different ram frequencies 800mhz - 1400mhz:D

Quote:

---

Originally Posted by jaredpace

Bench a video game at different ram frequencies 800mhz - 1400mhz:D

---

I came close CCC limits 900-1300MHz for mem :)

All tests done @1920x1200

http://img12.imageshack.us/img12/5499/scaling850900.png

http://img12.imageshack.us/img12/202...ing8501000.png

http://img12.imageshack.us/img12/470...ing8501100.png

http://img12.imageshack.us/img12/848...ing8501200.png

http://img12.imageshack.us/img12/331...ing8501300.png

http://img12.imageshack.us/img12/626...ing9001300.png

Enjoy! :D

dont forget to check for memory error correction (more details on overclocking page of my review)

Well, from the initial results it looks like HD 5870 responds to more memory bandwidth, but 100MHz mem OC doesen't tell us much. For all we know 150 more MHz on the memory would stop scaling. What we want to know is the point where overclocking the the memory stops giving more performance, as well as the point where overclocking core stops giving more performance. Here's a better methodology:

1. Download AMD GPU clock tool for HD 5870

2. Underclock both core and memory to half frequency (425/600) to keep the same Compute/bandwidth ratio.

3. Test at that frequency

4. While keeping the core @ 425MHz, start increasing the memory clock by some increment, say 50-100MHz, until it stops scaling or becomes unstable.

5. While keeping the memory @ 600MHz, start increasing the core clock by some increment, say 50-100MHz*, until it stops scaling or becomes unstable.

6. Repeat with as many programs as you care for.

7. Analyze

*Might be easier to have the same % increment as for memory. For example, if you use 100MHz increments on both, each increment is more substantial for compute resources because it starts at a lower frequency (450 vs. 600MHz.) If you want to have proper proportions, a 100MHz increase on mem has the same significance as a ~71MHz (70.833) increase in compute. In other words, multiply whatever you choose as the memory increment by 0.70833 to get the amount you should increment core by.

Quote:

---

Originally Posted by W1zzard

dont forget to check for memory error correction (more details on overclocking page of my review)

---

Link Please

http://www.techpowerup.com/reviews/A...D_5870/33.html

Quote:

---

Originally Posted by W1zzard

http://www.techpowerup.com/reviews/A...D_5870/33.html

---

Thank you.

Thanks lightman, wish elmore would let us know how he got his vmem up and clocked the mem at 1400mhz...
however, from your tests on the canyon flight FPS @ 850mhz core

memory mhz / FPS / fps Increase
0900 / 091.7 / 0 0%
1000 / 095.2 / +3.5 +3.8%
1100 / 097.9 / +2.7 +2.9%
1200 / 100.3 / +2.5 +2.5%
1300 / 102.4 / +2.1 +2.1%

According to this test, as the memory clock increases, gains are evident at 1200 -> 1300mhz. Even though they are diminishing as it goes higher, you are still getting benefits above the stock mem clock, which backs peoples assumptions that the card is bottlenecked @ 153gbps. Would like to see memory at 1400mhz, if it yields a ~2% increase over 1300mhz, it's even further proof.

Lightman's overall FPS is still increasing so his memory is not producing errors yet

Quote:

---

Originally Posted by W1zzard

"Overclocking the memory on these cards is quite different from any other card so far. Normally you'd expect rendering errors or crashes, but not with these cards. Thanks to the new error correction algorithm in the memory controller, every memory error is just retransmitted until everything is fine. So once you exceed the "stable" clock frequency, memory errors will appear more often, get retransmitted, but the rendered output will still look perfectly fine. The only difference is that performance drops, the further you increase the clocks, the lower the performance gets. As a result a normal "artifact scanning" approach to memory overclocking on the HD 5800 Series will not work. You have to manually increase the clocks and observe the framerate until you find the point where performance drops."
http://www.techpowerup.com/reviews/A...D_5870/33.html

---

Yes, I'm aware of ECC on Cypress. So far my memory won't cooperate @1400, but it is working @1350 (more tests needed to check for ECC)
This lets me believe 1300MHz should be stable.
BTW my core scales to 950MHz on default volts.

From my tests what caught my attention was Fillrate tests and how nice they respond to memory (for pixel) and engine (for texel) clocks! Also perlin noise seems to be purely GPU limited.

I think for what it's worth 1200MHz is a good compromise at this point of time.
This leaves AMD with doors opened for HD5890 with higher clocks and at the same time higher performance! It looks like 1GHz/1400 should be doable on current tech. using 6Gbps IC's (interconnect limited?).

Quote:

---

Originally Posted by Lightman

BTW first and foremost bottleneck is triangle setup. Same speed per clock as in RV770!
Let's look for more :yepp:

---

huh? how come?

but it cant be a big limitation, otherwise a 4870x2 would pull ahead notably in most tests...

thx lightman for the infos!
you dont happen to have a 4890 or 4870 or better yet 4870x2 so you can do exactly the same thing on that card in the same rig? :D

i threw the numbers in a graph:
Pixel shader, multi fillrate, perlin noise, vertex shader simple are not bandwidth limited... yes some of these increase slightly, but the boost they get from increasing the memory clocks and hence bandwidth by almost 50% can be ignored...

complex vertex shader, shader particles and fillrate single are clearly bandwidth limited... but the gains are linear and proportional, so the gpu is definately not bandwidth crippled or starved like some people suggested... i dont think that memory bandwidth is limiting the 5870... i think its internal bandwidth or some internal architecture bottleneck...

very interesting information :up:

Quote:

---

Originally Posted by saaya

thx lightman for the infos!
you dont happen to have a 4890 or 4870 or better yet 4870x2 so you can do exactly the same thing on that card in the same rig? :D

i threw the numbers in a graph:
Pixel shader, multi fillrate, perlin noise, vertex shader simple are not bandwidth limited... yes some of these increase slightly, but the boost they get from increasing the memory clocks and hence bandwidth by almost 50% can be ignored...

complex vertex shader, shader particles and fillrate single are clearly bandwidth limited... but the gains are linear and proportional, so the gpu is definately not bandwidth crippled or starved like some people suggested... i dont think that memory bandwidth is limiting the 5870... i think its internal bandwidth or some internal architecture bottleneck...

---

http://www.xbitlabs.com/articles/vid...on-hd5870.html

I'm still looking for this "bottleneck" on the architecture.
page three...

Quote:

---

Originally Posted by W1zzard

http://www.techpowerup.com/reviews/A...D_5870/33.html

---

Than you W1zzard :up:.

Regards. Chispy

Well, I'm getting my card on monday and should be able to do some more detailed tests, but at first glance it doesen't seem like bandwidth is that big of bottleneck. Either there's some obscure and unforseen bottleneck in the architecture, in which case we can probably expect some kind of very slightly modified but much faster fixed "RV890" chip to compete against GT300, perhaps in time to coincide with Nvidia's launch. More likely though, it's just immature drivers and broken optimizations that need to be updated for RV870. The fact that the card is launching relatively early, while eyefininty isn't working over CF, and SSAA is a broken blurry mess in the current drivers would seem to suggest this.

Again, there's no reason an enhanced and doubled HD4890 shouldn't outperform the HD4870X2, 4890CF, and the GTX 295. At the moment performance is good, but isn't anywhere close to where it should be.

sounds like a good combo with GDDR5 memory that is rated 5Gbps plus 1Ghz Core and 2GB memory
if you remember 512MB > 1GB on 4870 cards did boost preformace

Just so you guys know, clocking the card to 1/2 speed will not result in the performance "scaling" to 1/2 performance.

Quote:

---

Originally Posted by STEvil

Just so you guys know, clocking the card to 1/2 speed will not result in the performance "scaling" to 1/2 performance.

---

Dont let any facts get in the way of good ol 5870 bashing.:rofl:

I can see some experts here trying to track down some mysterious bottleneck crippling the HD5870, even though it out performs nvidias biggest and best dualcore monstrosity in some game benchmarks and poses a serious threat in most others. :)
Only nvidiots would portray a 40% performance improvement between models as too little, then claim to know about a mysterious bottleneck to back this opinion.
Its the same every model release when the opposing side feels threatened. :up:

Quote:

---

Originally Posted by Crankybugga

Dont let any facts get in the way of good ol 5870 bashing.:rofl:

I can see some experts here trying to track down some mysterious bottleneck crippling the HD5870, even though it out performs nvidias biggest and best dualcore monstrosity in some game benchmarks and poses a serious threat in most others. :)
Only nvidiots would portray a 40% performance improvement between models as too little, then claim to know about a mysterious bottleneck to back this opinion.
Its the same every model release when the opposing side feels threatened. :up:

---

Gotta say, I love this response, and agree. The 5870 is what it is....a "product", build on design, manufacturing, cost, and marketing/sales limitations. If the components are not equally matched, and thus there is hidden performance, so what. It is what it is. No one could ever claim that the 5870 components were perfectly tuned....to say within a few % of each other. It is "technically" interested what these test show, but in the real world what do they mean......they certainly have nothing to do w/ the decision to buy, or not buy.

And for disclosure's sake, I get my XFX 5870 on Monday.




.

Quote:

---

Originally Posted by dekruyter

Gotta say, I love this response, and agree. The 5870 is what it is....a "product", build on design, manufacturing, cost, and marketing/sales limitations. If the components are not equally matched, and thus there is hidden performance, so what. It is what it is. No one could ever claim that the 5870 components were perfectly tuned....to say within a few % of each other. It is "technically" interested what these test show, but in the real world what do they mean......they certainly have nothing to do w/ the decision to buy, or not buy.

And for disclosure's sake, I get my XFX 5870 on Monday.




.

---

I agree with you, but that 2% more performance only overclocking the memory is a sign that the card is a little bit bandwidth limited at least with same game, I will buy 2 of 5870 for sure but I would like to see some test with the memory at 1400mhz to see the difference......

Quote:

---

Originally Posted by dekruyter

Gotta say, I love this response, and agree. The 5870 is what it is....a "product", build on design, manufacturing, cost, and marketing/sales limitations. If the components are not equally matched, and thus there is hidden performance, so what. It is what it is. No one could ever claim that the 5870 components were perfectly tuned....to say within a few % of each other. It is "technically" interested what these test show, but in the real world what do they mean......they certainly have nothing to do w/ the decision to buy, or not buy.

And for disclosure's sake, I get my XFX 5870 on Monday.
.

---

This got everything to do with buying the best product and overclocking it to the max . We are on xtremesystems here ..
Most people here want to get the most of of the product which they have bought . And not only that , but we want to learn more about this product and squeeze every last bit of perfomance out of it .

You seem to be one of those few people on here that is not interested too much in this material . But that's ok too :up:

Quote:

---

Originally Posted by demonkevy666

I'm still looking for this "bottleneck" on the architecture.
page three...

---

my guess is having the units in 2 800sp blocks might cause problems with the hw scheduler... that should be possible to at least be improved if not fixed with driver updates tho i think...

Quote:

---

Originally Posted by hurleybird

Well, I'm getting my card on monday and should be able to do some more detailed tests, but at first glance it doesen't seem like bandwidth is that big of bottleneck. Either there's some obscure and unforseen bottleneck in the architecture, in which case we can probably expect some kind of very slightly modified but much faster fixed "RV890" chip to compete against GT300, perhaps in time to coincide with Nvidia's launch. More likely though, it's just immature drivers and broken optimizations that need to be updated for RV870. The fact that the card is launching relatively early, while eyefininty isn't working over CF, and SSAA is a broken blurry mess in the current drivers would seem to suggest this.



Again, there's no reason an enhanced and doubled HD4890 shouldn't outperform the HD4870X2, 4890CF, and the GTX 295. At the moment performance is good, but isn't anywhere close to where it should be.

---

ill correct myself, bandwidth IS limiting the 5870, but not by a lot...

yupp, i find it hard to believe that a 4870x2 is using the two gpus on it 100% efficiently and hence performs the same as a chip that has the same resources in one gpu... that makes no sense whatsoever...

not to mention 5870 is even slower on average than a 4870x2... theres def something limiting...

Quote:

---

Originally Posted by STEvil

Just so you guys know, clocking the card to 1/2 speed will not result in the performance "scaling" to 1/2 performance.

---

yeah, like with any chip there is a base performance... 5870s responce to memory bandwidth is about the same as most vgas though, it doesnt seem very memory bandwidth limited at all...

Quote:

---

Originally Posted by Crankybugga

Dont let any facts get in the way of good ol 5870 bashing.:rofl:

I can see some experts here trying to track down some mysterious bottleneck crippling the HD5870, even though it out performs nvidias biggest and best dualcore monstrosity in some game benchmarks and poses a serious threat in most others. :)
Only nvidiots would portray a 40% performance improvement between models as too little, then claim to know about a mysterious bottleneck to back this opinion.
Its the same every model release when the opposing side feels threatened. :up:

---

sigh, thanks for... contributing to this thread :up:

if only there would be more people like you who just ignorantly take things for what they are and mock people who try to understand and possibly improve things around them, this world would be a much better place... NOT :p:

you might wanna check out afghanistan next vacation, youd find lots of friends over there for sure :D
fertilizers? god made plants grow fast enough as it is, there is no limitation slowing it down, impossible! only a blasphemer would doubt gods perfect creations! ati is great! err god i mean! :lol:

Quote:

---

Originally Posted by CrimInalA

This got everything to do with buying the best product and overclocking it to the max . We are on xtremesystems here ..
Most people here want to get the most of of the product which they have bought . And not only that , but we want to learn more about this product and squeeze every last bit of perfomance out of it .

You seem to be one of those few people on here that is not interested too much in this material . But that's ok too :up:

---

well said bro! :toast:

and yes, if your not interested in this thats fine, but why would you bash people and call them fanboys and idi0ts if they are curious how the tech they bought works and how to make it faster? this is THE essence of overclocking and xtremesystems!!! posting here, on THE overclocking, tweaking and pc technology forum worldwide mocking this is quite bizarre...

this might be interesting to benchmark! id love to test a 4870 vs a 5870 with half its blocks disabled to see how big of a diference this makes!

Quote:

---

The computing cores can communicate on both local and global levels. ATI claims a considerable increase in cache bandwidth. Particularly, the speed of fetching data from the L1 cache is now as high as 1 terabyte per second while the bandwidth of the link between the L1 and L2 caches is increased to 435GBps. The L2 caches have become larger from 64 to 128KB.

---

xbitlabs keeps mentioning the reduced bandwidth "probably" causing some impacts at high resolutions compared to the 4870x2... they claim to have written this passage of the article before doing any tests, but i dont buy it ;)
im pretty sure they KNEW what perf was like when they wrote this part... :D

anyways, if bandwidth is really the limiting factor, then why doesnt the 5870 drop behind the 4870x2 notably at high resolutions and with high anti aliasing modes, and why doesnt the 5870 perform notably better at low resolutions where the memory bandwidth doesnt matter?

yes, you CAN see this trend, its definately there, but its veeery subtle... we are talking about a few percent points here, nothing mayor you would expect from the 5870 having more than 30% less bandwidth than a 4870x2...

i think i found something...
rv870 is a REALLY massive chip with a huge load of raw processing power... keeping all those sps busy is not easy... and i think thats whats holding the 5870 back...

http://img24.imageshack.us/img24/5228/d11vsd10.png

thread limit was only increased from 768 to 1024...
could this explain the limitation? 768 to 1024 is only a 30% boost... and a 5870 is roughly 40% faster than a 4890...

First of all, that's just the number of compute threads possible, and has nothing to do with limiting the shader power in games. Secondly, the 5870 can only run a maximum of 1600 / 5 = 320 threads, because you can only run one thread per group of 5 "stream processors", so in terms of DirectCompute even TriFire 5870's will not be held back by the thread limit, although QuadFire might be.

Quote:

---

Originally Posted by saaya

thx lightman for the infos!
you dont happen to have a 4890 or 4870 or better yet 4870x2 so you can do exactly the same thing on that card in the same rig? :D

i threw the numbers in a graph:
Pixel shader, multi fillrate, perlin noise, vertex shader simple are not bandwidth limited... yes some of these increase slightly, but the boost they get from increasing the memory clocks and hence bandwidth by almost 50% can be ignored...

complex vertex shader, shader particles and fillrate single are clearly bandwidth limited... but the gains are linear and proportional, so the gpu is definately not bandwidth crippled or starved like some people suggested... i dont think that memory bandwidth is limiting the 5870... i think its internal bandwidth or some internal architecture bottleneck...

---

they doubled registers and cache so internally it is fine.

Quote:

---

Originally Posted by saaya

i think i found something...
rv870 is a REALLY massive chip with a huge load of raw processing power... keeping all those sps busy is not easy... and i think thats whats holding the 5870 back...

http://img24.imageshack.us/img24/5228/d11vsd10.png

thread limit was only increased from 768 to 1024...
could this explain the limitation? 768 to 1024 is only a 30% boost... and a 5870 is roughly 40% faster than a 4890...

---

it is held back by the compiler. i dont see how this would be any different from rv770 though so obviously scaling linearly with shaders isnt goint to happen for ATi unless they change something in their memory system.

I'm benching my unlocked 720BE against a guy with that has a 5870 and i7 over at OCN... results are less than exciting (for me at least)

I just ran Crysis Warhead bench 0.33 (avalanche flythrough)


1920 0xAA

i7 @ 4.2Ghz Min: 29.55 Max: 46.81 Avg: 37.04

Phenom II x4 @ 3.6Ghz Min: 25.12 Max: 36.73 Avg: 30.99


1920 8xAA

i7 @ 4.2Ghz Min: 21.29 Max: 37.74 Avg: 28.65

Phenom II x4 @ 3.6Ghz Min: 18.24 Max: 29.33 Avg: 23.83



note: Unlock from X3 to X4 gave me a slight avg fps increase, and almost 2fps increase in min fps.

It appears since the min FPS numbers are all very close, they are revealing spots where the bench is GPU limited, and the Max FPS numbers are quite different, showing spots where the bench is CPU limited

Anyone who owns a 5870 and wants to add benches into the mix is welcome... I'll run the same bench if possible on my system and we can see what can be worked out about this. OBVIOUSLY a 3.6Ghz Phenom II is no match for a 4.2Ghz i7, but I would have though that the results would have been much more GPU limited in this bench. :confused:

crysis likes cpu as much as gpu

Not sure why you're less than excited. You're 600 mhz below him and only 5-10 FPS behind him in possibly the most intense game(graphically) there is. Still.

Nice results, are you 2 going to be doing any other tests together?

Quote:

---

Originally Posted by jaredpace

crysis likes cpu as much as gpu

---

Yeah, I'm going to try to do some other titles.

Quote:

---

Originally Posted by Gurr

Not sure why you're less than excited. You're 600 mhz below him and only 5-10 FPS behind him in possibly the most intense game(graphically) there is. Still.

Nice results, are you 2 going to be doing any other tests together?

---

Less than excited because I'm a hardware whore, and I don't need any excuses, no matter how weak, to buy new hardware :D

Considering our min FPS are still pretty much the same, means that we both would get roughly the same gameplay experience, so I still love my little engine that could Phenom II :)

The OP of that thread (the guy I'm benching against) seems to have dissapeared, so atm no, but I'm hoping to round up someone else with a 5870 and heavily OC'ed i7

I can't believe you guys thing it's really only 320 shaders.

Quote:

---

Originally Posted by demonkevy666

I can't believe you guys thing it's really only 320 shaders.

---

it IS 320 shaders. there are 5 alu's per shader. they are called stream processors. the 320 shaders are then grouped into 20 thread clusters.

Quote:

---

Originally Posted by Chumbucket843

it IS 320 shaders. there are 5 alu's per shader. they are called stream processors. the 320 shaders are then grouped into 20 thread clusters.

---

are actually 320 rather complex 5-stage computing subunits

which means that's the textures stream processors other stream processors are simple or general.

Quote:

---

The general principle of the computing section has not changed much in the RV870. It is still based on shader processors with superscalar design, each processor incorporating five ALUs four of which are general-purpose ALUs and the fifth is a special-purpose ALU capable of executing complex instructions like SIN, COS, LOG, EXP, etc. Besides the ALUs, each shader processor also contains a branch control unit and an array of general-purpose registers.

---

Quote:

---

When we are talking about 1600 stream processors in the RV870, we must keep it in mind that there are actually 320 rather complex 5-stage computing subunits. Provided sufficient code optimization, this design of the GPU’s computing section helps achieve a much higher level of performance than with Nvidia’s scalar architecture.

---

which is why nvidia has a shader clock and ati shader clock would be locked to the core speeds.

cpu is the bottleneck lol

I wish I could break the 3.8Ghz barrier to release some more potential outta these guys. Damn C0's.

Quote:

---

Originally Posted by hurleybird

First of all, that's just the number of compute threads possible, and has nothing to do with limiting the shader power in games. Secondly, the 5870 can only run a maximum of 1600 / 5 = 320 threads, because you can only run one thread per group of 5 "stream processors", so in terms of DirectCompute even TriFire 5870's will not be held back by the thread limit, although QuadFire might be.

---

I haven't found any reference for this to be true no where dose it say you can only enable 1 of 5 parts of the SIMD.

:shakes::shrug:

Quote:

---

Originally Posted by demonkevy666

are actually 320 rather complex 5-stage computing subunits

which means that's the textures stream processors other stream processors are simple or general.

cpu is the bottleneck lol

---

i dont see what you are disagreeing with. lets just stick with ALU because thats what they are. ATi can call them whatever they want. the 5th alu can also handle double precision btw.


realistically they say they will get more performance than nvidia but they dont tell you that their gpu's are heavily dependent on compilers to effectively keep the gpu under full load. not saying a gt200 is faster than rv870 though.

It'll be interesting to see if the DX11 changes affected performance

Obviously, it's hard to say since DX11 supposedly gives inherent performance boosts over DX10/10.1, but given that DX11 had some changes that might affect how the compiler works and how things are executed, im wondering if its possible one setup is bottlenecked

From what I've seen/heard too, the CPU power needed to keep up with one of these things might be a factor as well

4.2 isnt really heavily oced :D
thats kinda what all 920s max out at... heavily oced means 4.4-4.6, which IS possible with good chips on water or even good air :)
im quite surprised it needs that much cpu oomph...

especially at 1920x1080.... strange...

Quote:

---

Originally Posted by hurleybird

First of all, that's just the number of compute threads possible, and has nothing to do with limiting the shader power in games. Secondly, the 5870 can only run a maximum of 1600 / 5 = 320 threads, because you can only run one thread per group of 5 "stream processors", so in terms of DirectCompute even TriFire 5870's will not be held back by the thread limit, although QuadFire might be.

---

ahhhhhh, alright, thanks for clearing that up man! :toast:

Quote:

---

Originally Posted by Chumbucket843

they doubled registers and cache so internally it is fine.

---

well thats what they say... could still be limited internally somehow...
does anybody know how to disable parts of the gpu or get the driver to not use them like w1zz did in his 5870 review to simulate a 5850?

Quote:

---

Originally Posted by demonkevy666

cpu is the bottleneck lol

---

i dont think so... hwcanucks benched with an i7 at 4g or even 4.2 iirc...
and their numbers arent all that diferent from other reviews...

nascasho, only 3.8? is your cpu multiplier dropping to default multiplier under load? your probably limited by max tdp/tdc, ask evga how to disable or manipulate current feedback sensing of your cpu on that board either by bios or hardmod and you should get 4G+ :)

its usually a single small resistor that needs to be removed or pencilled to adjust the resistance and as a result your cpu will think current draw is low and wont throttle.

Quote:

---

Originally Posted by saaya

4.2 isnt really heavily oced :D
thats kinda what all 920s max out at... heavily oced means 4.4-4.6, which IS possible with good chips on water or even good air :)
im quite surprised it needs that much cpu oomph...

especially at 1920x1080.... strange...

---

Yeah, I just meant heavily OC'ed for 24/7 on air, he does have a 965 though. I'm more used to pre-D0 OC's too

I was pretty surprised as well with the results



He just posted a bench of downclocked i7, avg stayed about the same, but min fps took a BIG hit... worse than my 720BE now


i7 @ 4.2Ghz Min: 21.29 Max: 37.74 Avg: 28.65

i7 @ 3.2Ghz Min: 15.93 Max: 37.27 Avg: 28.46

Quote:

---

Originally Posted by demonkevy666

I haven't found any reference for this to be true no where dose it say you can only enable 1 of 5 parts of the SIMD.

:shakes::shrug:

---

Not what I was saying. What I was saying is that one thread is assigned to each group of five ALUs, unlike Nvidia's architecture where each ALU gets it's own thread. Because of this RV870 can only run a maximum of 1600 / 5 = 320 threads, which is way below the 1024-thread limit of DirectCompute11.

Quote:

---

Originally Posted by iandh

Yeah, I just meant heavily OC'ed for 24/7 on air, he does have a 965 though. I'm more used to pre-D0 OC's too

I was pretty surprised as well with the results



He just posted a bench of downclocked i7, avg stayed about the same, but min fps took a BIG hit... worse than my 720BE now


i7 @ 4.2Ghz Min: 21.29 Max: 37.74 Avg: 28.65

i7 @ 3.2Ghz Min: 15.93 Max: 37.27 Avg: 28.46

---

Errm, as his numbers show, the minimum is the cpu limited situation, the max is gpu limited, not the other way around his numbers prove that.

The phenom with 4 cores should give almost identical results in most games to a i7, 99% of games aren't cpu limited, the biggest difference between your results are the max not the minimum, meaning theres just something very different with his rig to yours, forcing AF, aa, or something, different drivers, something.

You can't remotely investigate cpu limits on two different rigs set up differently by two people.

As he's shown by dropping cpu speed, thats how you test cpu limits, identical system and setup, with a diff cpu speed. Which shows completely reversed results and conclusions compared to your initial "testing".


Either way, benchmarks which aren't a great reflection of in game experience, aren't very useful for testing the real limits behind a card. Most benchmarks are designed as just that, not necessarily to give you an impression of performance you'll recieve in game, but something for sites to use for years to come.

Most other games, and most in game testing should have minimum fps as gpu limited numbers, but the Crysis benchmark benches cpu just as much as gpu and the lowest numbers are normally the very heaviest physics sections.

But while the minimum has changed drastically, the average results showed what a 0.2fps difference, meaning that "minimum fps" result is rare enough that it is barely in the benchmark. The average result shows for that benchmark at least, that the 1Ghz difference in CPU speed, made a completely un noticeable difference in average fps/max fps. It killed the min fps, but probably had that min fps up for around a quarter of a second anyway, so pretty much irrelevant.

If you can draw any conclusions, its that your rig has a major problem thats severely effecting performance, the crysis benchmark isn't remotely cpu limited by a 3.2Ghz i7 and moving to a 4.2Ghz i7 makes no noticeable difference and, theres no point testing further till you sort out your rig. Frankly, you should be getting very similar average fps with the same card.

http://img9.imageshack.us/img9/8168/...erclocking.jpg

Definitely diminishing returns on the memory, if all you do is pump the memory the gains are negligible. But core & mem incremental increases seem to have a real benefit. I ran each benchmark twice (each is 3 loops long) and results never different more than a 0.2 fps (which makes the final result even more meaningless).

I was gonna simply have the image display but it was too damn big. Link instead.

Summary:

Crysis VH @ 1080p

850 core /1200 memory 37.2fps

890 core /1220 memory 38.34fps

900 core / 1230 memory 39.06fps

900 core / 1300 memory 39.33fps

With Crysis the minimum typically happens in area to area, or area to cutscene transitions, and definitely a faster CPU can help in these instances. Crysis has a long view distance, but most far objects are not rendered. When you quickly move into a new area, there's a sudden strain on the CPU to process a ton of new objects. I definitely found my min. framerates go up a bit moving from 3.2ghz to 3.6ghz on an i7.

Check out PCGH's GTX280 CPU scaling review. On Crysis, minimum framerates scale linearly with cpu clock speed, from 2.4ghz to 3.6ghz.

just out of intrest i'll run this bench for you...

i can see i'm gonna have to put some effort into oc'ing the cpu above 4.1 for this...

i'll be back in england and in front of my pc by tommorow evening hopefully... expect an update then...

and thanks for an interesting thread...:up:

Uh, oh, someone merge this thread with http://www.xtremesystems.org/forums/...d.php?t=235181, thanks!

Quote:

---

Originally Posted by nascasho

I wish I could break the 3.8Ghz barrier to release some more potential outta these guys. Damn C0's.

---

What's your vCore for 3,8?

Quote:

---

Originally Posted by zalbard

Uh, oh, someone merge this thread with http://www.xtremesystems.org/forums/...d.php?t=235181, thanks!

---

Done.

Quote:

---

Originally Posted by astrallite

http://img9.imageshack.us/img9/8168/...erclocking.jpg

Summary:

Crysis VH @ 1080p

850 core /1200 memory 37.2fps

890 core /1220 memory 38.34fps

900 core / 1230 memory 39.06fps

900 core / 1300 memory 39.33fps

---

Interesting, so 5-6% gain from a slight overclock ! Given the game you used, seems impressive to me ?

http://www.extrahardware.cz/files/im...pu_scaling.png
http://www.extrahardware.cz/files/im...em_scaling.png

http://www.extrahardware.cz/pretakto...adeonu-hd-5870

Quote:

---

Originally Posted by jaredpace

http://www.extrahardware.cz/pretakto...adeonu-hd-5870

---

It seems like the memory system complements the GPU well - neither appears to be a complete bottleneck at the speeds tested.

When they increased the memory by 100mhz they got the same boost as when they increased the core by 65mhz.

This could mean nothing but I tested with 4870 1gb in COD4 at 750/530 (same compute resource - bandwidth ratio as 5870) and at 750/900 to see the impact of memory bandwidth. Settings: 1440x900, All options max, 4xAA, AF max

750core 530mem
http://farm3.static.flickr.com/2549/...bd963579_b.jpg

750core 900mem
http://farm3.static.flickr.com/2662/...2c401421_b.jpg

crysis being much more shader intensive could mean memory overclocks having less effect on overall performance.

Quote:

---

Originally Posted by hurleybird

Not what I was saying. What I was saying is that one thread is assigned to each group of five ALUs, unlike Nvidia's architecture where each ALU gets it's own thread. Because of this RV870 can only run a maximum of 1600 / 5 = 320 threads, which is way below the 1024-thread limit of DirectCompute11.

---

so your saying the bottleneck is the thread dispatch and it's only being used at about 31.25% if it where redesigned to use all 1024 dispatches threads at once and not have those 5 alu's grouped. 5 alu is one SIMD. changing this to be all seprate alu shouldn't be too hard, the alu's them self are quite small already.

it's seem to me it's more like what ever is easy the programs will go for shorter times to code things.
easy isn't the best possible way to do things.

Quote:

---

Originally Posted by JimmyH

750core 530mem
http://farm3.static.flickr.com/2549/...bd963579_b.jpg

750core 900mem
http://farm3.static.flickr.com/2662/...2c401421_b.jpg

---

Thanks, nice work, JimmyH. Don't suppose you could run that again on your HD4870 at 750/574, 750/618 & 750/662. Those speeds represent the compute/bandwidth ratios of 850/1300, 850/1400, and 850/1500 on the HD5870's memory. Thank you :up:

Quote:

---

Originally Posted by jaredpace

When they increased the memory by 100mhz they got the same boost as when they increased the core by 65mhz.

---

You have to consider the values as percents, not the raw MHz. The 65MHz increase on the core is ~7.6% while the 100MHz increase on the RAM is ~8.3% - both very close, and the increase in FPS reflects this. Because increasing either the core or the RAM frequency nets noticeable performance gains, it appears that neither is bottlenecking the other (at the frequencies tested in the game tested). I'd imagine that in older games, the RAM will become more of a bottleneck to the FPS rate than would the core frequency.

Okay Mr. K6 - good point. They've basically raised the core & memory 8%. They get the same increase in framerates from either +8% core or +8% memory. To me this means that the 5870 could use all the more core or memory speed you could give it.

This card is going to give very good results to anyone who overclocks the :banana::banana::banana::banana: out it.

Quote:

---

Originally Posted by jaredpace

Okay Mr. K6 - good point. They've basically raised the core & memory 8%. They get the same increase in framerates from either +8% core or +8% memory. To me this means that the 5870 could use all the more core or memory speed you could give it.

This card is going to give very good results to anyone who overclocks the :banana::banana::banana::banana: out it.

---

Oh most definitely :D. I'm very much anticipating a stable release of Rivatuner so I can get to work on the voltages :). As it stands, AMD GPU Clock Tool isn't working with my card (drivers?), so I currently can't go above the limits of CCC (unless I'm using the program incorrectly). Anyway, with a little voltage, it seems these cores will easily do 1GHz+ on the GPU. I'd be interested to see not only the performance gains from this speed, but also if a memory bottleneck finally shows itself :eek:

Quote:

---

Originally Posted by iandh

I'm benching my unlocked 720BE against a guy with that has a 5870 and i7 over at OCN... results are less than exciting (for me at least)

I just ran Crysis Warhead bench 0.33 (avalanche flythrough)


1920 0xAA

i7 @ 4.2Ghz Min: 29.55 Max: 46.81 Avg: 37.04

Phenom II x4 @ 3.6Ghz Min: 25.12 Max: 36.73 Avg: 30.99


1920 8xAA

i7 @ 4.2Ghz Min: 21.29 Max: 37.74 Avg: 28.65

Phenom II x4 @ 3.6Ghz Min: 18.24 Max: 29.33 Avg: 23.83



note: Unlock from X3 to X4 gave me a slight avg fps increase, and almost 2fps increase in min fps.

It appears since the min FPS numbers are all very close, they are revealing spots where the bench is GPU limited, and the Max FPS numbers are quite different, showing spots where the bench is CPU limited

Anyone who owns a 5870 and wants to add benches into the mix is welcome... I'll run the same bench if possible on my system and we can see what can be worked out about this. OBVIOUSLY a 3.6Ghz Phenom II is no match for a 4.2Ghz i7, but I would have though that the results would have been much more GPU limited in this bench. :confused:

---

OK here is mine on:
PhII @3750MHz/2500MHz/1000MHz (core/nb/mem)
HD5870 default
DX10, Enth., 64bit on Vista x64

Quote:

---

DirectX 10 ENTHUSIAST 3X @ Map: avalanche @ 0 1920 x 1200 AA 0x
==> Framerate [ Min: 15.05 Max: 46.67 Avg: 32.30 ]

---

Quote:

---

Originally Posted by zalbard

Uh, oh, someone merge this thread with http://www.xtremesystems.org/forums/...d.php?t=235181, thanks!

---

This thread that we are now in is about the 5870's internal memory bottlenecking the card's performance.

The thread I purposely made seperate was to investigate CPU bottlenecking of the 5870 as a whole.

Quote:

---

Originally Posted by Ashraf

Done.

---

At your discretion of course as a moderator, but I think maybe these threads should be un-merged. They were for two totally different topics and merging them will most likely prevent the original goal of this thread's OP from being reached.

edit: Ashraf edited thread title to "5870 Bottleneck Investigation (CPU and/or Memory Bandwidth)" to reflect two different topics being discussed within thread.

Thanks!

i dont see any different scaling in benchmarks. the 4870 was 2x faster than rv670 and it had 2.5 times more shaders. i would not expect doubling the shaders to double effective performance. the problem might be the fact that there really isnt much to compare it to. might be l1 to l2 cache bandwidth.


_____________________RV770______RV870
Texture units ________40. ______80.
L1 cache bandwidth 480GB/s 1,000GB/s

L1 to L2 bandwidth 384GB/s 435GB/s

please unmerge the thread... we cant have a coherant discussion if everythread about the 5870 gets merged... meh....

Quote:

---

Originally Posted by purecain

please unmerge the thread... we cant have a coherant discussion if everythread about the 5870 gets merged... meh....

---

Yeah, it's pretty screwed now as far as coherency goes. I wish the person who reported the threads had bothered to read them before clicking submit... just because two threads have a similar title doesn't mean they are discussing the same exact subject. I can understand Ashraf's mistake because he probably just was going down the job queue and saw the thread titles, then hit "merge threads".

I asked Ashraf and he said that there isn't really an "unmerge" option, so I basically I'd have to start a new empty thread, and then delete all the posts from my old thread that are now in this thread.:shakes:

Got my 5870 today, but I can't seem to get the GPUclock utility to work. I'm using the RC7 drivers leaked from MSI, maybe that's the problem...

Quote:

---

Originally Posted by iandh

i7 @ 4.2Ghz Min: 21.29 Max: 37.74 Avg: 28.65

i7 @ 3.2Ghz Min: 15.93 Max: 37.27 Avg: 28.46

---

those numbers make no sense, idential max fps, but lower min fps... yet he still gets the same av fps? 0_o

this only makes sense if the min fps is REALLY short, like it drops to 15fps once and thats it...

Quote:

---

Originally Posted by demonkevy666

I haven't found any reference for this to be true no where dose it say you can only enable 1 of 5 parts of the SIMD.

:shakes::shrug:

---

Its depents on the game and the driver you can see it like this:

http://images.anandtech.com/reviews/...I/4800/ilp.png

So if instructions can be grouped together you can have quite a performance boost. Down side is if you cant group instructions you only have 1/4e or 1/5e of the performance.

I dont know if its true but i have heard the AMD compiler does a quite good job. Grouping up to 3-4 of them most of the time.

But if you have a heavy nVidia optimised game you can have lower value's and bad shader performance. (you might it 1-3 then)


Then about the performance of the HD5870. It does not seem to me memory bandwith limited. But i also think there is more performance inside this core then we see now. It might be driver related. It wont surprise me if we get up to 20% higher performance in the future.

The RV870 core is still new. And i think AMD could optimize the scheduling of the threads a bit better so you can keep those 1600 alu's fed with data. It would be nice if there was a way to see the load on those shader units. And compare it to the load on RV770 and RV790 cores. Dont forget those are well optimized in the last years driver releases.

Quote:

---

Originally Posted by jaredpace

Thanks, nice work, JimmyH. Don't suppose you could run that again on your HD4870 at 750/574, 750/618 & 750/662. Those speeds represent the compute/bandwidth ratios of 850/1300, 850/1400, and 850/1500 on the HD5870's memory. Thank you :up:

---

OK heres more:

750/575
http://farm3.static.flickr.com/2502/...a2681904_b.jpg

750/618
http://farm4.static.flickr.com/3434/...97c11f34_b.jpg

750/663
http://farm3.static.flickr.com/2578/...10d40b55_b.jpg

800/530
http://farm4.static.flickr.com/3432/...597305c5_b.jpg

800/575
http://farm3.static.flickr.com/2629/...481b9ef8_b.jpg

835/575
http://farm3.static.flickr.com/2487/...2cf224a3_b.jpg

The framerate does fluctuate a bit when standing still so I am taking screens at the minimum.

Interesting read: http://firingsquad.com/hardware/ati_...ng/default.asp

Quote:

---

Originally Posted by Mr. K6

Interesting read: http://firingsquad.com/hardware/ati_...ng/default.asp

---

Very interesting indeed . It seems that coreclocks give the most gains in the games they tested .

I actually can't wait to see what these cards can do when more voltage is given . And I also want to see what the little brother 5850 can pull out of it's hat in terms of overclocking :)

Quote:

---

Originally Posted by Mr. K6

Interesting read: http://firingsquad.com/hardware/ati_...ng/default.asp

---

Thanks for the link. Doesn't look like the 5870 is that bandwidth limited here. But it seems bottlenecked by something else. Most games return less gains than the increase on the core and memory. Poor drivers? Can't help thinking that the impressive power consumption of this card is actually could be the shaders sitting around doing nothing.

Anandtech power test with occt shows the 5870 actually uses alot more power than the other reviews suggest when loaded with a highly optimized application.

http://www.anandtech.com/video/showdoc.aspx?i=3643&p=26

based on jimmyh's cod4 benchmark:
(compute power to bandwidth ratio)
memory:
4870 speeds / 5870 equivalent / FPS / % increase
750 / 530 --- 850 / 1200 ----- 100 --- 0%
750 / 575 --- 850 / 1300 ----- 104 --- 4%
750 / 618 --- 850 / 1400 ----- 107 --- 2.9%
750 / 663 --- 850 / 1500 ------ 112 --- 4.6%
750 / 900 --- 850 / 2040 ------ 121 --- n/a
core:
4870 speeds / 5870 equivalent / FPS / % increase
750 / 530 --- 850 / 1200 ------ 100 --- 0%
800 / 530 --- 906 / 1200 ------ 103 --- 3%
750 / 575 --- 850 / 1300 ----- 104 --- 0%
800 / 575 --- 906 / 1300 ----- 107 --- 2.9%
835 / 575 --- 946 / 1300 ----- 110 --- 2.8%
http://www.xtremesystems.org/forums/...7&postcount=88

Lightman's 3d06 benchmark:
core / mem / FPS / + fps / + %
850 / 3600 / 091.7 / 0 / 0%
850 / 4000 / 095.2 / +3.5 +3.8%
850 / 4400 / 097.9 / +2.7 +2.9%
850 / 4800 / 100.3 / +2.5 +2.5%
850 / 5200 / 102.4 / +2.1 +2.1%
http://www.xtremesystems.org/forums/...1&postcount=23

Extrahardware.CZ Crysis 1920 × 1200, 4× AA
core / mem / fps / +fps / +%
memory:
850 / 4400 - 40,9 - 0 / 0%
850 / 4800 - 42,0 - +1.1 +2.7%
850 / 5200 - 43,1 - +1.1 +2.6%
core:
785 / 4800 - 40,1 - 0 / 0%
850 / 4800 - 42,0 - +1.9 +4.7%
915 / 4800 - 43,2 - +1.2 +2.9%
core and memory:
785 / 4400 - 39,3 - 0 / 0%
850 / 4800 - 42,0 - +2.7 +6.9%
900 / 5200 - 44,7 - +2.7 +6.4%
http://www.extrahardware.cz/pretakto...adeonu-hd-5870

Firingsquad Crysis 1920 × 1200, 2× AA
core / mem / fps / +fps / +% (from stock)
850 / 4800 - 31.6 - 0 / 0%
850 / 5272 - 32.3 - +0.6 +2.2%
850 / 4800 - 31.6 - 0 / 0%
930 / 4800 - 33.1 - +1.5 +4.7%
850 / 4800 - 31.6 - 0 / 0%
930 / 5400 - 34.3 - +2.7 +8.5%
http://firingsquad.com/hardware/ati_...king/page5.asp

Meh. You can get gains from overclocking core, or memory, or both together. You get higher gains (usually) from overclocking the core. Only in the game Batman did firingsquad get higher performance from overclocking memory vs. core. Conclusion: overclock core & memory as much as possible. Memory bandwidth isn't the bottleneck, otherwise we would have relatively no gain from core overclocking...:confused:?

Quote:

---

Originally Posted by JimmyH

Can't help thinking that the impressive power consumption of this card is actually could be the shaders sitting around doing nothing.

---

Yeah seems like it... jeez.

Quote:

---

Originally Posted by jaredpace

Meh. You can get gains from overclocking core, or memory, or both together. You get higher gains (usually) from overclocking the core. Only in the game Batman did firingsquad get higher performance from overclocking memory vs. core. Conclusion: overclock core & memory as much as possible. Memory bandwidth isn't the bottleneck, otherwise we would have relatively no gain from core overclocking...:confused:?

Yeah seems like it... jeez.

---

I wouldn't say it isn't memory bandwidth bottlenecked just because core overclock works. Memory bandwidth bottleneck isn't a hard capped bottleneck like the gpu core. From my experience overclocking 4870's memory from stock by over 10% returns less than 1% fps gain. So in comparison yes the 5870 is relatively bandwidth starved compared to 4870/ 4890. In batman it highlights memory's importance. core 9% + memory 12% increase fps by 10.5%

Jimmy - what situation maxes out memory bandwidth? Highest texture quality + quality AA filtering? I'm not sure if this maximizes the need for bandwidth. I know it loads up a greater amount of video memory potentially maximizing capacity, but how do you go about maxing out bandwidth? Is there a special test?

So you DO think it has a memory bottleneck? IMO it could definitely use faster memory. IDC @ anandtech says, "f you can overclock the GPU cores and see a performance improvement that exceeds that which comes from increasing the memory clocks then that is about as close to proof you are going to get that your compute system is not memory bandwidth constrained. "

Quote:

---

Originally Posted by saaya

those numbers make no sense, idential max fps, but lower min fps... yet he still gets the same av fps? 0_o

this only makes sense if the min fps is REALLY short, like it drops to 15fps once and thats it...

---

Yeah that's what I thought too, he got lower min fps than my 720be at stock, must be a fluke or something

Quote:

---

Originally Posted by jaredpace

Jimmy - what situation maxes out memory bandwidth? Highest texture quality + quality AA filtering? I'm not sure if this maximizes the need for bandwidth. I know it loads up a greater amount of video memory potentially maximizing capacity, but how do you go about maxing out bandwidth? Is there a special test?

So you DO think it has a memory bottleneck? IMO it could definitely use faster memory. IDC @ anandtech says, "f you can overclock the GPU cores and see a performance improvement that exceeds that which comes from increasing the memory clocks then that is about as close to proof you are going to get that your compute system is not memory bandwidth constrained. "

---

I don't know. Maybe look for games benchmarks where 4870 outperformed 4850 by significantly more than 20%. 16xAF could likely be one scenario. Colorfill test could show up limitations here too: http://www.techreport.com/articles.x/17618/6

Well the gpu core is doing the actual rendering work so increasing that usually gains more unless you are really badly bottlenecked by slow memory.

Has it been confirmed that all cards can have their voltages adjusted if flashed with the ASUS bios?

Quote:

---

Originally Posted by jaredpace

http://www.extrahardware.cz/files/im...pu_scaling.png
http://www.extrahardware.cz/files/im...em_scaling.png

http://www.extrahardware.cz/pretakto...adeonu-hd-5870

---

what cpu speed did they test with?
might stop scaling cause cpu is limiting?

thx JimmyH for the 4870 results! :toast:
so reducing 4870s bandwidth by 88% to the same bw/compute ratio as a 5870 results in a mere 20% performance drop. sounds like yet another hint that 5870 is NOT held back a lot by memory bandwidth...

Quote:

---

Originally Posted by demonkevy666

so your saying the bottleneck is the thread dispatch and it's only being used at about 31.25% if it where redesigned to use all 1024 dispatches threads at once and not have those 5 alu's grouped. 5 alu is one SIMD. changing this to be all seprate alu shouldn't be too hard, the alu's them self are quite small already.

it's seem to me it's more like what ever is easy the programs will go for shorter times to code things.
easy isn't the best possible way to do things.

---

i think hes saying the thread count is NOT a limitation cause even if all parts of the gpu are fully loaded its only using 30% of the max possible threads the dispatch processor can coordinate. and it can handle that many threads cause in xfire one dispatch processor apparently runs as master and oversees the threads running on all gpus in the system, hence the hint that in quad gpu configs the thread dispatch MIGHT limit.

Quote:

---

Originally Posted by Chumbucket843

i dont see any different scaling in benchmarks. the 4870 was 2x faster than rv670 and it had 2.5 times more shaders. i would not expect doubling the shaders to double effective performance. the problem might be the fact that there really isnt much to compare it to. might be l1 to l2 cache bandwidth.


_____________________RV770______RV870
Texture units ________40. ______80.
L1 cache bandwidth 480GB/s 1,000GB/s

L1 to L2 bandwidth 384GB/s 435GB/s

---

3870 to 4870 was a 150% shader unit boost that resulted in a 100% performance boost. this time we have a 100% boost of not only shader units but tmus and rops too! yet the perf boost is only 40% or even less in some cases... that would be as if 4870 would only have been 60% faster with a 150% logic boost instead of 100% faster. theres def something limiting...

l1 to l2 cache bw... interesting!
was looking for 770 figures but couldnt find any...
l1 to l2 barely increased at all... but then again, doesnt each 5way processor or alu or whatever you wanna call it its own L1? and each group of those shares the l2 right? the grouping hasnt changed, so then l1 to l2 bandwidth actually shouldnt matter and could have remained the same...

maybe it actually is if you normalize those numbers clockspeed wise for 770 and 870?

Quote:

---

Originally Posted by Astennu

So if instructions can be grouped together you can have quite a performance boost. Down side is if you cant group instructions you only have 1/4e or 1/5e of the performance.

I dont know if its true but i have heard the AMD compiler does a quite good job. Grouping up to 3-4 of them most of the time.

But if you have a heavy nVidia optimised game you can have lower value's and bad shader performance. (you might it 1-3 then)

---

it depends on the what it is doing .you can see here Ati is the intel of synthetic benchmarks.http://www.bit-tech.net/hardware/gra...ture-review/10. the wider you make a vector, the harder it is to keep under full load.

Quote:

---

Then about the performance of the HD5870. It does not seem to me memory bandwith limited. But i also think there is more performance inside this core then we see now. It might be driver related. It wont surprise me if we get up to 20% higher performance in the future.

---

on average one flop takes 1 byte per second of memory performance. this translates to 2 terabytes per second of required bandwidth for rv870 so every gpu made is bottlenecked from this. the only way is to further reduce the memory operation to calculation ratio. its already 100:1 but it must go higher.

As the 5850 is out i think its clear that something is holding the 5870 back, but what ?

Quote:

---

Conclusion

When you take the Cypress based Radeon HD 5870 and cut out 2 SIMDs and 15% of the clock speed to make a Radeon HD 5850, on paper you have a card 23% slower. In practice, that difference is only between 10% and 15% depending on the resolution. What’s not a theory is AMD’s pricing: they may have cut off 15% of the performance to make the 5850, but they have also cut the price by well more than 15%; 31% to be precise.

---

http://www.anandtech.com/video/showdoc.aspx?i=3650&p=14