650w is too much even if i look to the future upgrades because processors and gpu's are being made enery efficient on coming days so i thought 650w will be a overkill at max case i will use only 7850 not surely gtx 690 like cards.what do u say?
you would be able to run your system on the XFX pro 450W version if you wanted. my OCed i5 2500k and 560 ti never uses more than 350W even when running stress tests on the CPU and GPU. an i5 2500k and 7850 rig I built used even less than that. Normal gaming usage (playing BF3 for my tests) you're looking at under 250W.
I wouldn't bother with 600W+ unless it's a really good deal or just as cheap as a 450/500W.