Well that depends on what he is doing. In my SLI setup I run my BFG8800GTS 320 in the first slot which runs at its full settings. I run my EVGA8800GTS 320 in the 2nd slot because its alittle slower but I use the EVGA one to do all the PhysX. I dont use SLI in most games matter of Fact I dont think I use SLI at all. ha ha. I did notice that useing the fast card I get better Frames than the slow card in the first slot.