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I currently have a desktop with 6 GPUs ( 3x HD 5970s ) in non-crossfire mode. Unfortunately, it seems that Windows 7 64bit only supports up to 4 GPUs. I have not been able to find a reliable source to deny or confirm this.

If windows 7 has this limitation, is there a Linux flavor that supports more than 4 GPUs?

In-case you are wondering, this is not for gaming but high-speed single precision computing. With this current setup ( if I can find 6gpu support ) I am looking to reach 13.8 Teraflops.

Also, my motherboard does support 3 16x pci-xpress gen2 slots... and I have a 1500w powersupply plugged into a 20amp outlet. Windows is able to detect all 6 cores.. although, 2 of which displays the warning "Drivers failed to load".

To recap:

- Can windows support 6 GPUs?

- If not, does Linux?

Thank you.

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migrated from stackoverflow.com May 25 '10 at 13:13

This question came from our site for professional and enthusiast programmers.

    
Welcome to Stack Overflow TTK. Unfortunately, Stack Overflow is not the place for hardware related questions. This is better asked at the sister (or is it brother) site, superuser.com. In a few minutes, your question will be closed and migrated over. Good luck with the solution to your issue. –  Alan May 25 '10 at 3:32
    
Ah, Thank you! I was not aware of that site. –  Ryan Adams May 25 '10 at 3:34
    
Are you using the latest drivers? Seems like this might be a driver issue. I feel like linux will also depend on drivers –  basszero May 25 '10 at 14:28
    
Have you asked over here? forums.amd.com/devforum/categories.cfm?catid=390 They tackle hardware as well as OpenCL programming issues over there. –  K. Brafford May 25 '10 at 15:28
    
I am using the lastest drivers downloaded from the ati.amd.com website. I have not asked on those forums yet... but I will be sure to do so. Thanks! –  Ryan Adams May 25 '10 at 18:35
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1 Answer

Up to this point, I was not able to confirm or deny the support for more than 4 GPUs on Windows 7 64bit. However, I was able to find various users that have been able to run 5 and 6 gpus on Ubuntu 8.04 64bit.

http://forums.amd.com/forum/messageview.cfm?catid=328&threadid=122135

So, to answer my own question: If you are going to build a GPU Powerhouse utilizing >4 GPUs, currently the only documented solution involves 64bit Ubuntu.

Hope this helps someone.

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