As mentioned, a 750w corsiar should be fine for any single card. I personally use a 750w Antec TPN for my i5-750 @ 4Ghz and dual HD 5850's in crossfire and have power to spare. So crossfire or SLI with any cards that are not energy sucking pigs like the GTX 470 and 480 should not be no problem.
Master Rig: i7-5820k (4.4Ghz), Cooler Master Glacer 240L, ASRock Fatal1ty X99X Killer, 32GB Mushkin Redline, EVGA GTX 980ti Classified, 480GB AMD R7, 500GB Samsung 850 Evo, 2TB Samsung F3, Corsair RM850i, Corsair AIR 540, BenQ BL3200PT + LG 34UM67, FiiO D3 DAC, Presonus Eris E5's + Temblor T8
Last edited by Jhatfie; 08-01-2010 at 04:02 PM.