Originally Posted by SFixic "
Thank you for the quick reply. I have attached the image from the calculator.
I have a 600W PSU now and I had to take out one of the 6970's because it was very unstable.
You're welcome. Here's another calculation with more realistic results using more realistic settings. However, I need to mention that the calculator is likely inaccurate regarding how many watts the CPU is to pull when overclocked. One of the biggest factors is whether or not it's using the correct stock core voltage, and so far I've found that it can be way off which can make for differences of 50W or more in some cases.
Anyway, here are what I would consider more realistic results with more realistic settings (note: I don't know if 1.5V is realistic or not for 4.0 GHz, so I'm leaving it at 1.5V):
(click the image for the full size version)
Now, AMD recommends a 550W power supply to power a system that has just one 6970 in it which means that they would be recommending a 650W to power a system that has two in it. However, they are taking into consideration the possible purchase or ownership of a generic PSU. Most generic 650W power supplies have a much lower capacity than a quality 650W power supply due to what the PSU is rated for. A 650W generic PSU is rated for its peak capacity which can really only be sustained for about 1-2 seconds while a quality 650W is rated for a continuous delivery of 650W. So that means its peak is much higher which means that a quality 650W unit should be plenty.
However, if this PSU calculator is accurate at all (which I am doubting), then I can say that any quality 750W power supply would be plenty because it is recommending a PSU that can deliver 687W. This still feels like it's inaccurate on the high side to me, but I am a little bit short on time at the moment to do extra research.
Where can you order a PSU from, and what is your PSU budget?
Edited by TwoCables - 8/30/12 at 3:23am