Currently going to crossfire two Sapphire Radeon HD 7770 Ghz Edition Vapor-x together. I need a new power supply and have an extremely limited budget for one. The amd website says that if I want two crossfire these two cards I'll need a 600w power supply. I have picked out the Corsair Builder Series cx600 hoping this will be able to power these two cards. I have two questions, the label says at 80% it will be running 480w on a 12v rail. Will that be enough to power these two cards? If it won't will I be able to slip by on a Kentek 750w power supply? Yes I know it's crappy, but I have a tight budget and just need a good power supply to run these two cards.