Jakob
Discoverer
Yes OP should get Corsair CX430V2 if he is going for HD6850/7770 cause i've seen psu going boom and smoked by HD6850.
Only other recourse to this will be that OP forsakes the HD7770 GHz and HD6850, buys an AMD HD7750 [800MHz / 900MHz] with a orsair CX v2430W.
That is the only option I can suggest with constrained budget and high prices.