6970 CrossFire - how much PSU do I need?

v6maro

v6maro

[H]ard|Gawd
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Oct 10, 2002
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What minimum PSU wattage should I have to run in XFire?
 
A quality 750w would probably do it, as long as you don't have a ton of hard drives.
 
Running two 6970s in crossfire, 2500K @ 4.2, the highest peak I've ever seen my Kill-A-Watt read is 608 watts. I agree with the 750w suggestion, maybe 850w (which is what I use) just to be safe.
 
The minimum I would recommend is 650Watts if you are not going to force +20 powertune and accept some throttling on your speed.

If you want to force +20 and get the most performance possible from your card then I'd get no less than a 750 watt. Also note that unlocked 6950s use less power than a 6970 even at the exact same clocks and voltages.
 
Calwen said:
Running two 6970s in crossfire, 2500K @ 4.2, the highest peak I've ever seen my Kill-A-Watt read is 608 watts. I agree with the 750w suggestion, maybe 850w (which is what I use) just to be safe.
Click to expand...

So 608w from the wall, take into the 15% lost in PSU efficiency, that's roughly 520w being fed by the PSU. So a quality 700w unit that keeps you in the maximum efficiency range would be a good choice. If Calwen is using a GOLD rated PSU then add a few watts.
 
no less than a very high quality 750 watt unit to be safe. I would probably go with a 850 watt unit just to have plenty of room for any future upgrades.
 
I run a high quality 700w cougar psu with 6950s x 2 / AMD phenom x4 @ 4.0Ghz
No issues here yet.
 
go with 850 or higher; I would not feel safe using a 750 with two 6970s.
 
Depends on the CPU you use.
Two HD6950s with a 130W CPU or an overclocked 95, I'd say a 550-600W.
Two HD6970s with a 130W CPU or an overclocked 95, I'd say a 650-700W.
Two HD6970s with an overclocked 130W CPU, 750W minimum.

With my i5 750 overclocked to 4.1Ghz and overvolted to 1.35V, the max I ever see from my PC in a PSU stress test (CPU+GPU burntest) is about 690-710W out of the PSU.
 
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