id say up to 5,

i have a corsair AX750 with the following setup:
gigbyte ud5h mobo
intel i7 3770k cpu
1x 5970 - both cores at 830mhz
1x 5870 - currently at 901mhz
1x 7970 - at 1125mhz

been running stable for the last ~month also have 5 hard drives in the machine always on. i am able to game and mine with the 5870 perfectly aswell. seems perfectly stable so far, in the process of looking for a watt meter in my silly excuse for a country