Originally Posted by cdawall
My 7950's, Gigabyte Windforce edition, in Crossfire, at stock, pull about 235 W. BOTH CARDS.
Total system power consumption is literally 4 W away from 400 W. Stock speed of the cards is 900 MHz.
OC to 1200 MHz, a 33% OC(I know, killer OC capability on these GPUs), power consumption for hte card NEARLY TRIPLES, and the full system pull 836 W.
That's jsut two cards, and actually, I've been told my cards clock really well.
That's with a 3770K, 4.6 GHz, which pulls jsut under 100 W. You can figure ~75W for the board.
With a 3960X @ 4.6 GHz,(CPU voltage just 1.275 V), power consumption at stock is 498 W, which increases to 950 W.
And that is not having the cards maxed out...that's just 1200 MHz on the GPUs, no memory OC, and my GPUs can go higher.
850 W barely cuts it, depending on the rest of the system. And, i have killer 3770K (4.6 GHz @ 1.2V or less) and 3960X chips...most CPUs will pull signifigantly more than mine...I've seen very similar 3770K, for example, needing 1.225 V for 4.6 GHz, pull 20 W more than my chip.
I used to recommend 850W unit for dual GPU, 1200 W for three or four, but today, I have a hard time doing so. I am sure htere are going to be many instances where such PSUs will not be enough to max out the system. BOth nVidia or AMD...they got some killer chips with huge OC potential on both sides.