Multiple GPU without SLI or XFire MB support?

I think crossfire should work on any mobo that has multiple PCIe slots whereas SLI only works on the certified motherboards, therefore it should work on this motherboard in theory. However servers work differently and are used for way different purposes than everyday PCs (Gaming or Office) and so it might not work as expected, but I'd give it a try.

Well the question is what do you want to do with the cards? If you want to do some GPGPU, then running them independently for CUDA, f@h or similar will work just fine.

If gaming is your goal, then the lack of sli/xfire will not give you the GPU scaling you would want as the cards would run independently instead of in parallel.

I was assuming gaming. I figured I could crossfire a few cards just for fun until my kids try to boot their computers and figure out that I stole their video cards. What I'm hearing is two different answers, so let me narrow the question.

Can I use crossfire on a non-crossfire supported motherboard board and see improved game performance?

What motherboard is it?

Dell PowerEdge 6850 WC983 A00.

http://support.dell.com/support/edocs/systems/pe6850/en...

It had 1 8x and 3 4x PCIe slots. I'm familiar with what needs to be done to put a 16x card into a 8x slot, so that's not a problem.

I have same issue too. Looks Dell limited 16X video card to install in 6850 server....

Have you got any solution?

I've installed PCIe in Dell 2850 by melting off the back of the PCIe slot, allowing a 16x card to plug into an 8x slot. Works great. I figure I'm just about maxing out the bandwidth with an HD 5770 and going higher would provide diminishing returns. To crossfire a Dell 2850 I'd need single slot cards, which in my case would be a pair of HD 5670. I haven't tried it as it means crippling two other computer.

I have no reason to believe a Dell 6850 wouldn't work with a single card the same way the Dell 2850 does, but it's still PCIe 8x (I think PCIe 1.0) limited and that pretty much maxes me at a single HD 5770 before the bus gets saturated. The difference is in the Dell 6850 I have room to stick a bunch of cards in. Looks to be 3 double sized cards. That doesn't seem to help me much if I can't cross-fire them.

So to answer your question, I am 95% sure I can make one PCIe video card work in the Dell 6850. I haven't figured out if I can use Crossfire to make a second card work for gaming. I have figured out that Windows 7 Pro is limited to two physical CPUs, which is a bummer.