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CFX 6950s not working

Last response: in Graphics & Displays
March 12, 2012 9:00:22 AM

I recently built a new computer with the below specs. I cannot get crossfire to work properly. In Crysis Warhead I can only get 30fps on max setting when reviews show I should be getting 60. In Bf3 the game stutters so badly I cant play, or locks up and crashes. Other games new enough to use crossfire dont seem to even use it. The second card seems to just idle. Crossfire is activated and I have tried 7 different driver combos from 11.9 to 12.2 with the CAPS. Not sure what to do at this point. I have also tried reseating the cards. Also, just as a note, BF3 still stutters even without CFX enabled.


AMD Phenom II 975 BE 3.6Ghz
16GB ram 1600hz
Crossfire 6950s made by GIGABYTE
1200W PSU
GA-990FXA-UD3 for mobo.

More about : cfx 6950s working

March 12, 2012 10:19:35 AM

I know 5 people on the internet with this problem, but with 5850 crossfire and 6870 crossfire.

Processor 100%.

No AMD CPU under 4.2 GHZ can pull a crossfire. Mine is 1055T and every 100 MHZ OC adds substantial fps gain to my 5850 crossfire.

We are waiting for Ivy Bridge to upgrade. For best results, you can under clock the GPU's to 300-400 MHz, oc your CPU to 4.5 GHZ or upgrade asap.

Seriously underclocking the GPU's does tend to bring a few more FPS. The CPU is a major bottleneck, and it pains me to admit it, as im a slight fanboy due to AMD's lack of market share. I support the under dog for increased competition.
March 12, 2012 10:41:53 AM

How is that possible? In benchmarks 975 does just fine in game compared to intel CPUS. I dont see how it can be a bottleneck when my CPU is far above the requirements. I mean, Bf3 can run on a Core 2 duo and the 975 is rated as one of the best Gamer CPU on their chart.
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a b U Graphics card
March 12, 2012 11:25:41 AM

Did you check whether the CPU hits 100% while gaming?
March 12, 2012 11:33:04 AM

After alt tabing it seems to be at around 80%. Anyhow this cant be a cpu bottleneck. I can get 60-80 fps in BF3 before I dies and stutters and freezes. How would a CPU bottleneck even make sense? No, 975 is no i5 2500k but it is WAY beyond what I need for any of these games.
March 12, 2012 11:35:27 AM

Also, what AMD cpu could I upgrade to to fix this issue? I have a AM3+ socket. Will 8150 work?
a b U Graphics card
March 12, 2012 11:35:32 AM

I too don't think this is a CPU bottleneck, because a 975 should handle 6950s in CF well.
Did you check the temps of both the cards and the CPU?
March 12, 2012 11:44:59 AM

Temps are all fine. nothing higher than 60c. I did overclock to 3.9ghz just to test. No change. So im pretty sure CPU thing is ridiculous. ARMA 2 also pulling only 30fps. Doesnt seem to make use to Dual GPUs in any games except BF3 which lets me play for about 1min before going stutter crazy so badly it crashes game. Metro 2033 actually seems to work though with 60-80 fps on Very high 1080p Dx11 4xAA. Im totally lost.
March 12, 2012 11:46:55 AM

Second card is completely Idle. MAster card idles at 250hz when not under load, slave idles at 0hz on both clocks. I have used both cards as master so its not a broken card. WTF.
a b U Graphics card
March 12, 2012 11:47:03 AM

Is the 30 FPS capped? I mean, are the frame rates capped at 30?
Are you sure you haven't enabled AA or any other setting in CCC?
a b U Graphics card
March 12, 2012 11:50:15 AM

Second card is completely Idle. MAster card idles at 250hz when not under load, slave idles at 0hz on both clocks. I have used both cards as master so its not a broken card

I'm guessing that's because of the motherboard's PCIe running times.

It says here that the first slot is running at X16 whereas the second is only running at X4.
But I guess that lane speeds wouldn't make much of a performance dip.
March 12, 2012 11:59:44 AM

You miss read motherboard. I have 2 16x slots
a b U Graphics card
March 12, 2012 12:02:07 PM

My bad, I didn't see there were 2XPCIe X 16 slots.

What about in CCC?
March 12, 2012 12:29:50 PM

Yeah its other 16x. Crossfire is on. Detects both cards in CCC and third party stuff. I do get a performance boost in BF3 for the like 30 second I can play before it stutters to death. Runs at about 60-80 fps. Could it be the ram? I ordered 16gb but I put a 4gb stick in as a stopgap till my 1600hz 16gb comes in the mail.
a b U Graphics card
March 12, 2012 12:35:12 PM

I was wondering if AA or any other setting was turned up on CCC? Is it?
March 12, 2012 6:44:33 PM

It is a CPU bottleneck, no AMD cpu can pull 6870 crossfire or higher. Just for you, ill dig up an old thread.

Heres some old charts.

On those old charts you dont see the new 2500K, so the gap is even wider.
There is nothing im more certain of it being a CPU bottleneck.

Than at the end OP finally gets 2500K ends his bottlenecking problem. I cant wait to upgrade myself. These 5850 crossfire is almost as potent as a 7970 but only costed me $250. But AMD cant pull their own graphics cards weight.
March 13, 2012 7:38:07 AM

It sucks how no AMD cpu can pull their own graphics cards in CF.
a b U Graphics card
March 13, 2012 8:03:35 AM

chaosgs said:
It sucks how no AMD cpu can pull their own graphics cards in CF.

But what about the 1100T?
March 13, 2012 6:30:18 PM

I have a 1055T and would need it to run at 4.2-4.5 to pull my own 5850 crossfire. So imagine someone with something yet faster. Got a crossfire 7950/7970? Dont worry you cant get AMD CPU's with that. I wish they would pick up the pace.