lol wut. This post is completely bogus. Please do some research before misinforming others. First off you can only estimate how much a gpu will draw, it is impossible to know exactly what it will draw. The only thing that can be measured accurately is the total wattage pull from the socket. Second, there is ZERO difference between multi rail and single rail. With single rail you don't have to worry about balancing the draw over the rails, that's it. Third, it is very much possible for what he is asking. Two GTX 295 which draw more than four 6970's can be powered in that rig with a certain 600w psu with no problems. It has been done before. Google it. However, he would do fine with any psu that has at least 80 amps on the 12v rails to allow headroom for overclocking.