4850@750Mhz vs 4870

[TheScavenger]

Can we get a list of expected overclock and maximum voltage per cooling option?

Is this about right?

Stock cooler with higher fan speed
1.3V? 800MHz?

Upgraded air
1.4V? 850MHz?

Water
1.5V+? 900MHz+?

I second that idea. We need a chart!

[dnottis]

Q6600 G0 L737B @ 3.6Ghz
Asus P5K-E/WiFi (Bios 1012)
OCZ DDR2-8500 DDR2-1066 4096MB Memory
1/2" ID Masterkleer, Swiftech MCP-655, Thermochill PA120.2 Rad, D-Tek Fuzion, Swiftech Stealth
Thermaltake ToughPower 1000watt PSU
HIS HD4870 790/1000
X-Mystique 5.1 Digital Dolby Sound Card
Lian Li PC V-2000
Acer X222Wbd 22" LCD

[keiths]

dnottis, if you would, do a run with your 4870 set with GPU@625 and memory@stock. This would contrast with the results of gurusan's 4850 set to GPU@750 and memory@stock, and the stock 4850s & 4870s. Though I think we already know what the outcome will be

[keiths]

http://www.xtremesystems.org/forums/...light=Accelero

Comparing gurusan's numbers with the above results, 4850@910 /w water cooling edges out a 4850@700 /w an Accelero at load, and destroys it at idle. I would definitely say water FTW To be fare though, kiwi was limited to ccc overclocking at the time.

[dnottis]

Guys, I have a waterblock coming for this very soon, in the meantime I installed a TT Duo Orb. Idle is 40's, load 60s. Great air cooler imo.

In the other thread they talk about not leaving the VRMs uncooled. Are the VRMs the grey things I dont have sinked or the smaller black things I do have sinked? TIA.

[Calmatory]

I didn't read the whole thread, only the few first posts but anyway.

You can't really say how much card is held back by the memory speed or GPU speed. It depends on the game/app and settings used. High resolutions with AA/AF require more bandwidth than low resolutions without them. Thus one can't really give any kind of percentage estimates that would apply in all apps/games. It depends so much in the game/app. For example in Company of Heroes my 7300GT is very badly GPU bound, giving very linera FPS increase as I increase the GPU clock. Then in Trackmania Nations Forever the same applies for memory, but not for GPU. I can underclock the GPU from 500 to 400 without big FPS drop, but if I underclock the memory from 500 to 400, the performance drops by almost 20%. Oh, and ATITool's 3D Cube FPS seems to scale well with memory BW.

[dnottis]

dnottis, if you would, do a run with your 4870 set with GPU@625 and memory@stock. This would contrast with the results of gurusan's 4850 set to GPU@750 and memory@stock, and the stock 4850s & 4870s. Though I think we already know what the outcome will be

Here it is...

[keiths]

That was unexpected. Matches gurusan's score @810, doesn't match chw.net's 4850 score, and far exceeds their 4870 score. They used a quad@3.0, but variance in platform has only had a minor effect on the results, while this is out of the park different. Something's not right, your underclocked 4870 is closing in on a 280gtx.

[dnottis]

Welp the CPU is at 3.6Ghz, ram at 1066Mhz. The CP showing the GPU speed was opened right after the run. It was definitely run at 625/900.

[ExodusC]

So we still have no definitive answer on how much (if at all) the GDDR5 memory helps the 4870's performance?

I'm assuming I should just go with a 4850 and an aftermarket heatsink and do some overclocking.

[adamsleath]

question:
does having faster memory make memory amount less critical?
ie i have this idea that having higher bandwidth will mean that vram memory is less likely to be maxed at high res/settings, but is this true or false?
if true would mean more vram on lower bandwidth cards might help
or if false, it's the opposite of what im saying and high bandwidth needs more vram

nv approach 1gig vram high bandwidth
ati approach...not yet 1gig vram and high bandwidth...

[Miwo]

Heres my Vantage run at 750/1000. This was on "High" preset, because i can't run the Extreme because I can't select 1920x1200 as a resolution (I'm on a 1080p TV)
For comparison purposes, Techreport's scores @ High on a QX 3.0GHz: http://techreport.com/articles.x/14990/14




Going off GPU score only,

4870 @ 750/900: 4886
4850 @ 750/1000: 4485 <--- My Score
4850 @ 625/1000: 3851

So.... in Vantage High,
80&#37; higher bandwidth of the 4870 over my 4850 @ 750/1000 yields an 8.9% increase in score.
20% Increase in Core Speed (750MHz vs 625MHz) yields an increase of 16.4% in score.

Hope these results were a little helpful in shedding more light on this subject . Obviously, certain scenarios will favor memory bandwidth, and some it may not matter so much. Will do some more testing when I get around to it.

[Calmatory]

It doesn't matter are you using 50 GB/s or 500GB/s VRAM if it runs out. It has to be swapped to the system RAM and then back when needed, and thats why it is so slow. Basically higher FSB might help if VRAM runs out, but does it matter if FPS is less than 2 anyway?

[zaraza]

Miwo can you ran crysis if you have it? Dang im in the same position, im curious to see if the ddr5 really benefits it that much. Heck 5-7 &#37; according to http://www.ocforums.com/showthread.php?t=567799&page=3 is not much. Look at posts 65 and 66.

[Miwo]

Sorry, this is pretty much a fresh Vista64 install and i dont have any games installed yet. Just vantage for now

Here is Vantage High again @ 925/1000MHz

Techreport for comparison:


48&#37; Core increase(925MHz) over Stock = 5141 GPU Vantage High (33%)
20% Core increase(750MHz) over Stock = 4485 GPU Vantage High (16.4%)
Default 625 / 1000 = 3851 GPU Vantage High (Baseline Techreport's Results, sorry didn't test stock )

Definitely see some diminishing returns here!!!. Will have to do vmem mod tomorrow and play around with the DDR3. My card is definitely dying for some bandwidth.

Temps are 48C under 1.55v using Accelero S1 + 120mm Delta TriBlade + 70mm YS Tech. Coolaboratory Liquid Pro. I think Power Circuitry is holding me back or something. ATITool artifact tester fails with 1 pixel incorrect (I can't see any yellow flakes), Vantage passes fine, and my temperatures are fine. 4870 does have an extra 6pin connector as well as beefier vregs. Still, all in all very fun card to play with for under $200. I'll probably see if I can run this around 1.45-1.5v @ 900MHz for 24/7 usage

[dnottis]

That was unexpected. Matches gurusan's score @810, doesn't match chw.net's 4850 score, and far exceeds their 4870 score. They used a quad@3.0, but variance in platform has only had a minor effect on the results, while this is out of the park different. Something's not right, your underclocked 4870 is closing in on a 280gtx.

Alright, I know why. In the screenshot Enable Overdrive is disabled (no check in the box) so actually it was running stock. Still a good showing for a stock HD4870. I'll rerun at 625/900 a bit later when I'm home.

[zaraza]

sweet, thanks Dnottis, I am really close to pulling the trigger on either card. Just no 4870's available and 4850s are on sale like crazy lol.

[dnottis]

sweet, thanks Dnottis, I am really close to pulling the trigger on either card. Just no 4870's available and 4850s are on sale like crazy lol.

Here is the corrected HD4870 @ 625/900 you guys wanted. The other pic (in previous post) is updated also -

[keiths]

You must have goofed and copied the old picture onto your new post instead of the other way around; your new numbers are the same as the old numbers. 22.575 average.

[grimREEFER]

so, what do u guys reckon, a 4850@800mhz would be faster than a stock 4870?

[zaraza]

still tryin to figure that out lol. all we have the the crysis GPU test and Vantage. It looks like yes? but we dont know the effects that the bandwidth will have on the card.

[Truckchase!]

I didn't read the whole thread, only the few first posts but anyway.
.......

Read my posts.

[aldamon]

still tryin to figure that out lol. all we have the the crysis GPU test and Vantage. It looks like yes? but we dont know the effects that the bandwidth will have on the card.

I think the fact that everyone has to search and compare and bench to find significant performance differences between these cards speaks volumes. The circumstantial evidence is starting to pile up.

[keiths]

Lower, but still way over stock 4870 results from chw. I added your numbers anyway. Why the more results the better, to spot the trends and anomalies. Hopefully more people will respond to get a better feel.

[biohead]

dnottis how does 750/900 (or lower mem) compare to 750/1000 (or higher mem if possible). the main question is how bandwidth hungry these cores are.