FYI, this is what it says on the PSU:
http://www.xbitlabs.com/images/coolers/1000w-psu-roundup-2/9p7s.jpgThats "only" 1320W on 12V lines, which is all that GPU's use.
Even at stock speeds (edit) 300Wx3 + 375W = 1275W for the GPU's alone. Granted, thats TDP, while mining at low memory speeds it might be lower than that, but you have other devices that need 12V, not in the least the CPU.
