Not to harrass you on the power supply mate but just to be on the safe side I wouldn't run a 7970 and 2550 on such clocks off any 650, nevermind an OCZ one. Just go Corsair as the PSU is one of the things you do NOT want to save money on. Just my thoughts though.
It's more than enough power, I have researched this loads and also I don't understand what everyone has against OCZ power supplies, a couple of my friends have them and they say that they are great.