I also posted this on the BOINC message boards under the GPU boards, but this board seems a lot more active.

I'm looking to add a bit more crunching power to the computer that has been getting most of my BOINC credit, and the most obvious solution seems to be to add a second GPU.

Right now I'm using a FirePro v7800 (similar to Radeon 5850), which is out of my price range to add a second, so Crossfire Pro is not really what I'm looking for. I do, however, have two empty PCI Express 2.0 x16 slots, and an 850W power supply with plenty of connectors.

My question is: what do I have to do to add a second GPU? If i just drop in a second card will BOINC detect it just fine and start using it? Can I run one AMD card and one nVidia card? Can I run work for different projects on each card concurrently? Any other problems to look out for?

As a side note, while I'm not looking to do a Crossfire or SLI setup right now I may later, and perhaps someone else reading this will be. How does BOINC react to that? I've heard that BOINC doesn't see a set of GPUs in SLI/Crossfire as a sinle GPU, but will it see each individual one still? What about the single PCB, dual GPU cards, like Radeon 6990 or the coming GTX 590? Any other considerations?

Thanks in advance!

Hi koooooj,

you can take a look onto my computers; one has two ATI-Cards without crossfire, another has one ATI and one nVidia, works fine with different project( actually 5 GPU-based projects are running there).
It needs some tricks to get that running (ATI-cards are not detected when no monitor or dymmy-plug is attached) and on the mixed system the monitor should be attached to the ATI-card. But beside these startup problems everything runs fine and stable.

I have two different nvidia cards in my machine and had to add

<use_all_gpus>1</use_all_gpus>

to the options in cc_config.xml for it to pick up the second GPU..

Apparently boinc has some selector engine that will only pick "the best" gpu and leave the other one unused.. not sure why..

But that flag makes it use all of them.