Quad XFX Radeon 6950 problems

[arrowdynamic]

I built mining rig with 4 x XFX Radeon 6950 (crossfire x3) (black, one fan each).
With 3 cards it runs problem free and very stable.

When I put the 4th card in, MSI afterburner or Sapphire Trixx do not start. I get the error "Unable to initialize display driver wrapper". Crossfire and guiminer works fine, but I can't control all 4 fans in the cards. I have reinstalled drivers and hotfixes etc. Can this be a windows 7 update problem?
I have 1000W power supply so that should not be a problem.

I have noticed similar trouble with this card:
http://forum.bitcoin.org/index.php?topic=7341.0

However, someone seems to be running 4x6950 fine according to the hardware comparison:
https://en.bitcoin.it/wiki/Mining_hardware_comparison

My question is:
Is it possible to mine with 4 6950 cards or should I return the 4th card?

All comments and suggestions are highly appreciated!
Arrow Dynamic

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[arrowdynamic]

Okay..

So far I haven't been able to resolve the "unable to initiate the display wrapper problem".
These cards also heat like crazy.

Right now I have the rig set up with three cards, each spaced out so the air circulates and keeps the cards cool.
This set up works, but it's a bit disappointing to not have 4 cards running.

Does anyone have experience getting 4 6950 cards running without the display wrapper problem and without heating problems?

I haven't played with the bioses etc. but I don't think it'll help this one. Ideas?

Mining hardware comparison shows someone running 4x6950, but most of others like this video give me the impression that in general 4x6950 cards are not done.
http://www.youtube.com/watch?v=pk3FEYkCvJE

Any ideas on how to resolve this problem and run 4 cards?
I already decided to return the 4th card, but if I hear from you now, I'll keep it and make it work.

[Fuzzy]

I have 3 XFX, 3 Sapphire and 3 Powercolor 6950 cards, and the XFX have the worst heatsinks ever. The Sapphire has heatpipes, and the PowerColor has 2 fans AND heatsinks, but the XFX just has these really short fins slapped straight onto the die.

However, the PowerColor has longer than avg screws sticking out the back that will protrude into the fan blades if another PowerColor card is behind it. If you are able to exchange any of them, put the new card at the top, as the heat cascades from card to card, since the upper card suck air off the back of the card below, thus the upper card runs hotter = hotter air takein in by the card above that etc etc...

[1.21gigawatts]

I have this same problem but with 4 MSI 6950 cards.  4th card give the same error message as you.  3 cards and it's happy.  I even reinstalled Windows thinking something goofy happened with the drivers.

My hypothesis is that with 4-6950 cards, it's pulling too much power from the PCI-E, so I bought a PCI riser with molex to try.  I will be trying in the next few days.
I have a 1200watt antec power supply, so PS is not an issue

[arrowdynamic]

I have this same problem but with 4 MSI 6950 cards.  4th card give the same error message as you.  3 cards and it's happy.  I even reinstalled Windows thinking something goofy happened with the drivers.

My hypothesis is that with 4-6950 cards, it's pulling too much power from the PCI-E, so I bought a PCI riser with molex to try.  I will be trying in the next few days.
I have a 1200watt antec power supply, so PS is not an issue

I don't think power is the problem.
At one point I had 1000w powering the computer plus 2 cards. 3rd card powered by 700w and 4th powered by 650. Now I have 1000w and that should be fine.
I think if it was a power problem it should freeze and not give this error.

If I wanted to explore it more, I'd go for linux and see if the drivers over there work better.
I'm returning my 4th card today. I tried alot. I'll be happy to share my experiences.

I don't think anyone is running 4x6950. Prove me wrong if you are.

[1.21gigawatts]

so i tried the pcie riser with molex and still no go.

I gave up on the problem, and took out the 4th 6950 in the machine and replaced it with a 5830 and all is well now.
The 4th 6950 I just moved to another computer.

[Departure]

its not your cards its After burn, I also had the same problem with after burn when I installed my 3rd 6990... gave the exact same error, so I just used aoclbf to adjust fans and overclock/underclock then used GUIminer for mining, Now im just using aoclbf for overclocking, fan control and mining....