Psu help

My build thus far is:

CPU: amd iix4 athlon 750k

GPU: sapphire r9 270

M'board: asrock fm2a75 pro 4

RAM: 8gb kingston hyper x

HDD: 1tb wd caviar blue

Cooler: Coolermaster hyper 212 evo

For the case I'm pretty much set on getting the corsair carbide 200r windowed, but the psu...

I want to oc and in the future I will add a second 270, so in terms of wattage what would you suggest?  I was thinking along the lines of 750w as the fractal design integra r2 is only €6 more expensive than the corsair 600w where I shall be buying the parts ( ).

*Btw everything listed above the case I already have. 



750w is kinda overkill. 600 or 630w should be enough.