How many GPU's can Drivers take ?

Hi working on a Folding at home Computer and have 4 GTX 295 V.C.'s in it now the MoBo has 7 slots for 7 video cards.

The question is right now with the 4 cards would the drivers take another 3 cards for a total of 7 vc’s and 14 gpu’s 0,1,2,3,4,5,6,7,8,9,10,11,12,13

Thank you

IIRC the driver would but the BIOS might not, but don’t quote me on that. I think tmurray talked about this in some thread.