A-Grey - I dont' know the exact wattage needs but I've had no problems with my current Thermalright 850w. With that said I do have a "P3 Kill A Watt" meter which can measure volts, current, and watts with reasonable accuracy. I'll set it up later tonight and figure out how many watts my PSU is pulling from the outlet (granted this isn't perfect but it will give an indication of what my system is pulling). With my hardware I can't specifically measure just the CPU and GPU (only what the whole system is pulling). I remember the number being less than I thought it would be when I first tried the "Kill A Watt" meter out. Will post back in a few hours after I get home from class.