ATI Radeon HD 4000 Series discussion

[Luka_Aveiro]

Doubt it, but if they did than this could imply that micro-stuttering is a rather easy thing to fix through drivers. If they already knew about it for a while, let's say at least a year, then the fix is probably not very easy.

I suspect vSync fixes it, i only noticed micro stuttering when I had 8800GT SLI, Crysis @ very high vista x64 40 fps seemed like 18fps, weird thing :s

I didn't try vSync though, although pasting 60fps, micro-stuttering isn't noticed because frames displayed are enough to keep fluency.

[snipper_cr]

All this talk about dual GPU cards brings back memories of my old Rage Fury Maxx. I thought we were on to something then, putting two GPUs on a card. Guess it took a couple years longer till the idea came around

[Hornet331]

the idea is even older then the rage maxx -> just look at the voodoo chips, or custom military grade flight simulators.

[zerazax]

Looks like jimmyz has the updated GPU-Z shot + oc results in his review thread

W1z updated GPU-Z to correctly read 4850 and he's of the belief it is indeed 800SP's...

[Marvin54]

yumi waiting two 4870 XD

[disruptfam]

hmmmmmmmm

x58/nehalem and 2 x 4870x2 looks to be my next upgrade

[w0mbat]

New GPU-Z detects 800SP: http://www.techpowerup.com/gpuz/mq8dr/

[Cooper]

New GPU-Z detects 800SP: http://www.techpowerup.com/gpuz/mq8dr/

now the question is if it detects or displays predefined value

[Luka_Aveiro]

now the question is if it detects or displays predefined value

AFAIK, displays predefined value.

[w0mbat]

But AFAIK W1zzard has got his HD4850 yet, so he should be able to detect it.

[DilTech]

Gah! You guys are confusing the duplication of data on the framebuffer with memory bandwidth. They are two completely separate things!

I'm not sure how else to explain it but I'll try.

The duplication happens when the host CPU sends texture and other reference data to the GPU over the PCIe bus. This happens only when needed...if a texture is already in local memory on the GPU it's not resent. At this point both cards have the same data.

Bandwidth however is used to do the work to actually render the frame. Reading texture data into the chip, writing buffers back out to memory etc. This is not duplicate work as it's being done for two different frames. This is stuff a single GPU would have to do twice anyway so it's not wasted bandwidth.

This statement is correct regarding STORAGE.



This statement is incorrect regarding PROCESSING. A single card would have to do this job twice over two frames. Two cards do the same thing somewhat in parallel.



No it is not the same as a single 256-bit memory bus. It certainly isn't the same as a single 512-bit one either but it's definitely closer.

I quote you
but the gpu aren't doing the same job, because they are processing different frames
so they can use 90% of same assets, but doing different job at 100%

I'm going to break it down for both of you....

When using AFR, with 2x256bit each frame is limited to the 256bit bus of the gpu rendering it, just like a single 256bit bus. That's plain and simple. If a frame needs more bandwidth then the single 256bit bus offers, guess what happens? The gpu Chokes, on you guessed it, it's single 256bit bus. As such, even in AFR, 2x256bit is NOTHING like a 512bit bus.... With a 512bit bus, it has the full bandwidth available on every single frame.

See the difference? No matter how you break it down, or what claim you make, the fact is that 2x256bit just will not function like a single 512bit but rather closer to a single 256bit bus.

[Hornet331]

quite interesting that they droped tiling, cause there you would have a bandwidth advantage.

[Luka_Aveiro]

quite intresstening that they droped tiling, cause there you would have a bandwidth advantage.

And latency increase

[Stuen4y]

I dont see how the 4870 would launch at the same time as the 4850, no pics no benchs, i find it hard to believe that it will launch the same time.

Actually the cards are being produced right now because of the gddr5 memory delay, so don't worry about ati, their schedule is very strict and it looks like they will succeed to produce the cards in time. There were samples of 4850 in late May, so it looks that the only reason for this delay is the memory.

P.S. Are there yet any predictions for the difference between 4850 and 4870 on same gpu clocks?

[adamsleath]

i thought with afr that one gpu was rendering each alternate frame
so you have the potential for increased fps using "afr", but you also have all the limitations of each card for each frame that is rendered. i think that is how it works.
am i right? or wrong?

based on what aliG said i think it comes down to shader power, i dont know where the choke point is reached with bandwidth and frame buffer size, and what exactly happens when frame buffer is exceded and or bandwidth exceeded? i guess youll get a lag/judder or somesuch

must be some benefit to having 512bit bus and 1gb ram and heaps more shaders in the newer cards.

assuming a non gpu bound situation you are obviously gunna get more fps if the cpu can feed the gpu more info.
as for microstutter, are there any ways of choosing diffrent settings to eliminate them diffrent drivers or something? anyone fixed their ms problem/s?

getting some more fps is all well and good when it comes to a dual card setup, but only so long as you are happy with the limitations of each single card's abilities / choking points / bottlenecks....shader power /core speeds / etc. wtf am i talking about?; i got no clue but if someone would like to enlighten me im all ears

[AliG]

microstuttering can't be fixed with just a simple driver change (at least not with today's drivers, probably at some point nvidia and ati will find a way around that through software), for now only design changes by ati or nvidia can eliminate it

[SEA]

About stutter again -

Depends on the game. In something like a racing game where the game world is going by rapidly and the view is changing at a high speed the stuttering can be very noticeable. In an RTS or RPG and most FPS's it won't be that noticeable.

Then, does that mean that stuttoring usually looks like single jumps time to time?

And the issue isnt about how long it takes to render the frame on each GPU. It's about the timing of when frames are delivered to each GPU and how long each rendered frame stays on screen.

I thought frames are being delivered to the screen as they ready (if sync waiting is off, of cource).

[emoners]

just wanna ask, how much power does the 4870 consume? will it be needing 2x6-pins or 1x6-pin + 1x8-pin?

[Macadamia]

2 6-pins is the official design, although I suspect vendors might use GDDR4 to cut costs and with less power usage 1 6-pin would be okay.

[perkam]

Looking forward to 48x0 launch, as are all the Nvidia users after those GTX 280 and 260 numbers

Perkam

[emoners]

2 6-pins is the official design, although I suspect vendors might use GDDR4 to cut costs and with less power usage 1 6-pin would be okay.

Thanks!

[Genius_pt]

Looking forward to 48x0 launch, as are all the Nvidia users after those GTX 280 and 260 numbers

Perkam

Well said!

[Stuen4y]

2 6-pins is the official design, although I suspect vendors might use GDDR4 to cut costs and with less power usage 1 6-pin would be okay.

4850 is also with 2x6pin connectors, although is equipped with drr3 memory, so there is no way 4870 to be with only one . I'm quite sad, that ati left behind the 6+8pin configuration. It looks like it brings bad luck to GTX 280, just like R600 a year ago .

Looking forward to 48x0 launch, as are all the Nvidia users after those GTX 280 and 260 numbers

Perkam

They shall start pray and go to fire a candle in order ati to fail in their effort .

[StimulatedBoy]

"The other thing I have to say before I wrap this all up is that I’ve tested the HD 4850, and I’ve tested it in Crossfire. Now, if I hadn’t tested those cards I may have been more impressed with the GTX 280, but I have. I’ve seen the performance figures the cards put out. We also know the price on a pair of HD 4850s is going to be under $600 AUD, while the new GTX 280 in stock form seems to be launching at the absolute cheapest in Australia in the low $700 AUD area. Ouch."

- Tweaktown...

http://www.tweaktown.com/reviews/146...ion/index.html


ps. Forgot the link. Quote from last page http://www.tweaktown.com/reviews/146...hts/index.html

[perkam]

"The other thing I have to say before I wrap this all up is that I’ve tested the HD 4850, and I’ve tested it in Crossfire. Now, if I hadn’t tested those cards I may have been more impressed with the GTX 280, but I have. I’ve seen the performance figures the cards put out. We also know the price on a pair of HD 4850s is going to be under $600 AUD, while the new GTX 280 in stock form seems to be launching at the absolute cheapest in Australia in the low $700 AUD area. Ouch."

- Tweaktown...

WTF !!! 0_o And those aren't even the 4870s

Perkam