You are incorrect. That test setup uses the nVidia GTX 590 which is a dual gpu with a 365 watt TDP. The HD7970's TDP is 250W. I would avoid the CX600 for powering a nice setup like that. The CX series is Corsair's economy line. Bump up to the AX series and you'll be fine.
Ok I really don't think that 600 watts will be perfect, 700watts is always a better option. I haven't tested the processor myself so I have to have some reference right but according to my logic 700watts will be good at least for future upgradibility.
I know those situations are rare when both the CPU and the gpu are stressed out to the maximum but still just to be on the safe side I suggested 700watts.