Does it have to be SLI to CUDA?

Grimgoth · 1 Feb 2010 at 17:41

I just realised I didn't know the answer- if I wanted to number crunch over more than one graphics card, do the graphics cards have to be exactly the same (as if you were to SLI them) ?

If no, how disparate can they be? do they need to be of the same generation, ie no mixing a 260 with a 8600, or is this fully possible?

edit: oh and if they are not SLI, do they then need a dummy vga plug to be used?

theoretical and practical answers please

TheTross · 1 Feb 2010 at 18:45

Not sure if they need to be the same generation or not, but I'm pretty sure you'll need to use a dummy plug if running Vista or W7 (and then extend the display over the two cards I think). If you're using XP then you shouldn't need a dummy plug.

Snapshot · 1 Feb 2010 at 18:47

No, you must turn SLI off. The cards can be different but I believe they must use similar architectures to prevent driver issues. If they are different the weaker one must be in the first PCI-E slot otherwise it'll drag the better one down to its own level.

Biffa · 1 Feb 2010 at 20:02

http://folding.stanford.edu/English/WinGPUGuide

JonJ678 · 1 Feb 2010 at 20:45

I can say that an 8800gt will not fold in the same machine as a 280gtx for love nor money, but an 800gt and a 9600gso are quite happy together.

miniyazz · 1 Feb 2010 at 21:54

JonJ678 said:
I can say that an 8800gt will not fold in the same machine as a 280gtx for love nor money, but an 800gt and a 9600gso are quite happy together.

What sort of problems did you encounter?

My ATI cards didn't want to fold when I put them in my system (with a 9600GT already installed) - came up with an error code of some description, basically saying they were unstable, which I highly doubt because they were at stock (even tried underclocking them) and I stress tested them with no problems.

SiriusB · 1 Feb 2010 at 23:56

If you monitor is fairly recent [last 2 years] then it will more than likely have dual input - usually 1 x DVI and 1 x VGA or some other combo. Either way, if you have two inputs, you can just plug on into each card.

I have my "main" card plugged into the DVI input and my secondary into the VGA input on my Dell 2001WFP, works like a champ. Also means I can take a look at the other output if need be. I sometimes hide running apps over that side if I dun want them cluttering the place up

JonJ678 · 2 Feb 2010 at 18:57

miniyazz said:
What sort of problems did you encounter?

Ubuntu told me the machine was unstable, same error that happens if I push the gpu clocks too high. Windows told me the hardware was unsupported and gave me a link to the single thread cpu client. I never solved this, though running out of money and selling the 280gtx avoided the problem neatly enough. Couldn't find anything promising through Google either

miniyazz · 3 Feb 2010 at 01:37

JonJ678 said:
Ubuntu told me the machine was unstable, same error that happens if I push the gpu clocks too high. Windows told me the hardware was unsupported and gave me a link to the single thread cpu client. I never solved this, though running out of money and selling the 280gtx avoided the problem neatly enough. Couldn't find anything promising through Google either

Hmm sounds like it might be the same error, not really sure - my error came from within the Folding program - too many EUEs or something - rather than the OS itself. I never tried my 4850s without the 9600GT though as it seemed likely that my solitary 9600 would produce better PPD than both 4850s together :rolleyes: