So... I have a pair fo GTX480s in SLI and I'm curious how much of a difference slipping in a low end gpu to dedicate for physics might make. For the record... yes I know I'm going overboard... but I love excess. I just wonder if there is so much power already in the system that adding a dedicated PPU would make no difference at all or perhaps cause a performance hit from putting physics computing on a different pcie channel. If there is actually some decent performance to be gained here... what would be the best modern GPU to look at for dedicated PPU? Perhaps the new 420 coming out soon?