I'm currently looking into buying/building a new system, and I plan on putting an AMD 6950 in since it can easily overclock. Question is, what power source do I want? I put the system I was looking for into a configurator (just for ease) and instead of the Corsair 650AX I was told I needed at least 700w for the card.
I seriously hope you do not take Phaedrus advice as gospel, Honestly he has just told you a 400W supply will be ok! He hs not asked what your entire system will be comprised of, therefore has no Idea at all what PSU you need!
Scroll down page, 6950 = 500W minimum 6970 550w minimun.
Now if you are planning on Unlocking that 6950 with 6970 bios, then yes Minimum is 550w, but No-one in thier right mind goes with the bare minimum in PSU, simply the most important part of your PC, the part that if it fails, in best case scenario stops your pc working till you replace it, and in worst case scenario, takes out your CPU/Mobo?Gpu along with it when it goes POP!
And then saying 700w would be OVERKILL for Crossfire 6950, OMG, that would be the bare minimum i would expect to see!
Wolfeman, your Corsair 650w is a great choice, pefect for stable singel 6950/6970 configuration, It will also allow you to upgrade that card in the future as well when they come out!
If you want Crossfire, get the 750W model or greater!
I understand you folks don't know me, and maybe don't trust me as much. But in this case, I'm right. In that Guru3D article, with the GPU at full stress, their system was pulling 312W from the wall. That means after losses from the power supply. We don't know how efficient their power supply was, but probably in the 80-85% range. That means that running Furmark the system was pulling, at most, 250-275W. With that type of load, it doesn't really matter what his CPU is, anything short of a very overclocked 980X would be safe, especially since it's unlikely he'll be running Furmark and LinX at the same time all day.
The 6950 is at the "break point" between 400W and 450W for me. If it makes you feel better I can recommend a 450W instead. But I'd bet cash money that if he chooses a quality 400W power supply (Antec NeoECO 400C, Antec Earthwats EA430D, SeaSonic S12II 430W, OCZ StealthXStream 400W, OCZ StealthXtream II 400W, Rosewill RG-430, etc.) he'd see no power-related issues at all.