• Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
    Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.

6950 crossfire issue

ManofGod

ManofGod

[H]F Junkie
2FA
Joined
Oct 4, 2007
Messages
13,080
Ok, looks like there is a 6950 crossfire issue that seems to be a problem no matter the cpu you use. The basic problem, I have 2 6950's unlocked and both work fine by themselves.

However, once I do crossfire, I end up with negative scaling in just about everything I do. (Crysis, crysis2, low score in 3D Mark 06 and so on.) GPUz has confirmed that both gpu's are enabled and are working at full speed.

I have a 1090T overclocked to 3.9GHz as well. Crossfire was working with the 4890 + 4870 combination but not with these cards. What is going on and what is the solution. I have tried 11.11 and 12.1a beta drivers but that did not help. (Also used the latest caps.)

Any ideas?
 
Have you tried each card individually to see if both have no issues without xfire? PSU issue, connection issue? xfire bridge? No system specs in sig makes it a little harder.
 
1090T 3.9GHz, 16GB DDR3 1333 GSkill ram, 2 x 6950 Colorpower unlocked, 2 x 1TB harddrives, 1 x Bluray drive, Thermaltake Toughpower 750 Watt, Asrock 990FX Extreme 4 mainboard. Does that help? Oh, and using one crossfire bridge.
 
Well, I'm sure other people will have other ideas, but offhand, I'd take a stab at:

1) try each card individually and see how they perform to try and rule out any card issue
2) long shot, but you have the cards in the first two slots, right?
3) what's the temps on the cards - also check gpu clocks under load to see if they're throttling for any reason
4) do you have ULPS disabled?
5) Power connections from psu --> gpu's
6) PSU in general - looking at some reviews, the 750W TT Toughpower has had some issues, and if you're only having problems under heavier xfire load, could be psu related.
 
I have not tried the switch back yet but that is a good idea. (I have a bios switch on each one which will help.) :D

Also, 3d Mark Scores:
Vantage: 25348
Mark11: P8177

Any good or do they sound off?

Also, Heaven score of 1936.
 
Your 3dm11 score does seem alittle low. Although AMDs seem to bottleneck cf and sli especially with more powerful cards.
Definitely set them back to6950s and compare.
 
I get P9300 and P33,000 respectively overclocked but i'm not unlocked. I see good scaling. My guess would be your CPU isn't putting enough juice to those cards.

You can say i'm nuts...but i've had Phenom II....basically the same core. Framerates going from PII to SB are night and day.

Now...I just tryed adding a third HD 6950 and saw negative scaling (in eyefinity). I did see a little boost in BF3 but that was about it.

It might just come down to how powerful your CPU is after all when it comes to getting the most out of a multi-GPU set-up.
 
Your 3DMark scores aren't too far off, honestly, if at all.

Not quite a direct comparison but, I get ~21,500 in Vantage and ~7500 in 11 with my main rig, x4@ 3.725 and stock 6950s, for whatever that's worth.

I also agree with the above, Phenom II will score poorly in physics tests and hinder your GPU scores in 3DMark, by quite a bit.
 
Last edited:
spacing guild said:
I get P9300 and P33,000 respectively overclocked but i'm not unlocked. I see good scaling. My guess would be your CPU isn't putting enough juice to those cards.

You can say i'm nuts...but i've had Phenom II....basically the same core. Framerates going from PII to SB are night and day.

Now...I just tryed adding a third HD 6950 and saw negative scaling (in eyefinity). I did see a little boost in BF3 but that was about it.

It might just come down to how powerful your CPU is after all when it comes to getting the most out of a multi-GPU set-up.
Click to expand...

His score just seems a little low. My old i7 920 rig (@ stock, turbo on) with 2 560TI's scored 8450 in 3dm11 and that was @ 2.813 GHz. With turbo off @ 2.693GHz it scored 7950. No idea with vantage.
However, the same rig scored only 18.5k in 3dm06. Whereas my current rig @ 3.6, with 2 4870's scored almost 20k. :confused: Go figure.

Hopefully when my other 6950 shows up I can post a comparison.
 
Well, I switched back to the original bios but that did not help. One thing I found strange was that the heatpipes on the main card were warm but the bottom card felt cold. It does not appear that the second card is even being used.
 
ManofGod said:
Well, I switched back to the original bios but that did not help. One thing I found strange was that the heatpipes on the main card were warm but the bottom card felt cold. It does not appear that the second card is even being used.
Click to expand...

If your second card is cold there is a problem. Both of mine get hot when gaming.
 
Check actual speeds of each card under load - use something like afterburner - and see if theres throttling.
 
Well, I figured out part of the problem: I am using DDR3 1333 Ram that runs at 9CL. It is definitely affecting the benchmark scores but gaming is better than it was. (I can max crysis at 1920 x 1080 with realifesis and it plays very smoothly.) Oh well, it is not as fast as I expected but they are working well otherwise.
 
You must log in or register to reply here.
Back
Top