6950 DCII Crossfire problems

G

Gmac

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Mar 23, 2013
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I recently purchased a second Asus 6950 DCII card (used) to use in crossfire with my existing one. Card works, and system runs fine until I install the crossfire adapter(s).

System boots up but freezes on windows 7 loading screen with one, or both crossfire adapters installed, yet will boot up fine without adapters on. ive swapped positions of the cards and the crossfire adapters but the problem still persists. Is there a setting in the mobo bios that has to be enabled to have crossfire working? I have not been able to find one.

Ive read other people having somewhat similar problems and the result was an underpowerd psu, but one with 700w should be enough?

system specs

Asus 6950 DCII x2
Asus M5A97 mobo
AMD FX 8120
Enermax Modu 87 700w PSU
 
I have a 6950 DCUII in Crossfire and had problems in certain games because I had overclocked the motherboard chipset too high (X38) without upping the voltage. Are you overclocking?

How long have you owned the PSU? Maybe the capacitors have aged?
 
Motherboard is new, no overclocking done to it. Ive had the psu about 6 months.

My motherboard supports crossfire, but seems to be maxed at 4x on the second pcie slot. Would this cause a problem? Everything works great, up until I put on the crossfire bridges and restart the pc.
 
I was able to boot into windows with the crossfire bridges installed. However, now when I enable crossfire in the CCC I get a BSOD.
When I restart and boot back into windows the graphics driver stops working.
 
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Reinstalled drivers. Now whenever trying to enable crossfire in CCC system goes to BSOD. BSOD gives atikmdag.sys error.
 
I would also set both cards to stock clocks, if you haven't already.
I had an issue when I added my third 6950 causing BSODs, I lowered the clocks on it to stock and it was fine. I was able to bump them back up a bit once crossfire was back on.
Sadly my rig doesn't have enough pci lanes to benefit from a thrid card
 
I think I narrowed the problem down to a bad bios on the second card, the one that was flashed to a 6970. Running just that card, and bios switch set to factory bios gpuz shows its stats as being a 6970, not a 6950 like it should. With bios switch set to second position, I get a BSOD on startup.

So the guy I bought it off of screwed up when he flashed the card, flashing both bios's to a 6970, and somehow screwing up the second bios. Is there a way to flash the second bios, even though the card gives a BSOD on startup, or am I stuck to trying to reflash over the factory bios and hope it dosent fry the card? Or should I try flashing my 6950 to 6970 and see if that works?
 
Took the good bios from the 6950, and flashed the 6970 back to stock 6950. But same thing happens when I try to enable crossfire in CCC, I get a BSOD.

Flashed motherboard to newest bios, fresh install of windows, fully updated. Nothing else but chipset drivers and videocard drivers, and still get a BSOD.

Both cards seem good, tested both in BF3. At a loss as what to do.
 
I used ati winflash to save the bios from the good card, then used that to flash the 6970 back to 6950. So both cards now have the same bios. Both should now be identicle.

Im going to uninstall the videocard driver, and go back to a much older one and see if that works. But I have my doubts.
 
That probably won't work. You're able to play games/Furmark, etc on the new card when installed by itself?
 
yep, tried the new one in BF3. And it works just as well as the old one does.
 
My motherboard has 2 pcie slots, one 16x and one 4x. As far as I know the second slot is locked at 4x. So could it be possible that there is not enough voltage to the 4x slot, and when I enable crossfire there is not sufficient power going to the second card so I get a BSOD? One is a blue slot, the other is black.
 
The power comes primarily from the 6 & 8 pin connectors from the PSU. Your PSU is borderline, if you know of anyone who has a 850w+ to try it's worth a shot.
 
I installed some earlier drivers, and have since got crossfire to enable. However I do not see any improvement in frame rates in BF3, its the same as running a single card. Dont have any other games installed at the moment to test.

Using catalyst 12.1 right now.
 
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You should open a couple gpu-z windows and monitor GPU usage for both of your cards to ensure they are working in BF3. I don't play BF3 much, but I did notice a decent FPS increase when I got my second 6950 installed.
On a side note, when I got my third card for tri fire, it choked my system down, and my gpu's wouldn't run at full load with all 3 cards. One card hit like 80% usage, and the other two was stuck around 30%/40% each and my overall performance decreased in games. The third pci slot on my board is only an x4 lane. I figured either my board or my CPU (not enough pci lanes) was causing the bottleneck.
 
Ran gpuz while playing some games, Second card seems to be running up to %90. However gpuz seems to have switched my cards, gpu1 is actually gpu2, and vice versa. Anyway to change this? It does show that the second card is "synchronized with master".

Even if the second card is working, I am seeing zero increase in fps in the games I tried. Played BF3, Borderlands 2, Crysis 2. Ive got the latest cap profiles installed.
 
Could be because of the old drivers. You really need to get it working with at least 12.8 IMO. Crossfire drivers have come a long way in the past year.
 
As per your suggestion I tried out the 12.8 drivers, and I am able to enable crossfire without a BSOD using those drivers. However I am still not getting a performance increase in any of the games ive tried. Crossfire logo is displayed in the top right hand corner when playing those games.

12.8 are the newest drivers ive got to work, 13.1 will BSOD when enabling crossfire.
 
I am on 13.1 with cfx water cooled 6950s. BF3 is fine but Arma3 crashes before I get in game. I have on and off problems with my cards for awhile now. I flashed them to unlock shaders only and no o/c quite some time ago and they worked great for awhile, but eventually started acting up.

Not sure if it is the shader unlock that caused it or what, I am thinking of ditching them for a single 7970.
 
Just an update, I finally got this working right. Seems I dident have the catalyst profiles setup correctly.

Games seem to be working correctly, almost getting double the fps now. :D
 
I had the profiles installed, but dident realise they had to be enabled seperatly in the CCC.

Ive also changed my motherboard for one that can do PCIE x16 / x16, and not x16 / x4
 
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