I have a rig running 8 gpus, 4x570, 4x580. It pulls 1180w from wall that means a bit less on psu side, around 900w. Recommend you using quality psu and risers, a good 80+ gold/plat 1200w psu will be enough for your 6 gpus, if you want to expand later you can add another psu to your mobos psu b slot. Im using same gpu and mobos on some of my rigs, just send me a pm if you need help on tuning clocks and modding bios. I have seen many ppl getting bad results from those cards, if you cant get 30+ just tell me.