8+ gpu system

[twoBitBasher]

Lets say I got a machine with 4x5970 and then I'd like to add a couple more 5870s to the system using Xen virtual pc(directed i/o). Lets also say I have ubuntu to run the 5970s and only the two 5870s are passed to the virtual pc. Does this work or do I need to set two virtual pc:s and just use the ubuntu as hypervisor? I assume the amd drivers loaded by the ubuntu won't like the two 5870s it sees at boot time...

Also what is the maximum number of GPUs that the bios is able to initialize? I know that the fastra2 project ran into this problem with their 13 gpus.

[multi#lord]

From what I understand after having skimmed through a number of topics is that the limit is 8 GPUs. Some argue the limit is imposed by OS or driver, while others say its a limitation on the BIOS. I read a while back the fastra did have over 8 GPUs, but they were having quite a number of issues to get it to run properly. On the other hand, someone in a forum mentioned receiving a motherboard from Asus with a special released BIOS to increase the memory space allocated for video cards, in order to run more than 8 GPUs. Though it would be neat to have 8x 6990, or even 7990 if released.

[neo_rage]

It is AMD driver limitation.