So I just bought a new Xfx 850w Black edition PSU, everything seems to be working fine except that whenever I turn off the computer I can hear a really loud, high pitch whine, which I assume is coming from the PSU as it never happened before installing it. I had just installed a Asus GTX 580 direct cu II as well but I couldn't imagine its that as its at its worse when its turned off. I thought at first it only happened then but I just noticed that actually the sound is still there when the computer is turned on just much much quieter. Is there anything I can do to resolve the problem myself or is it just a case of having to return the PSU to amazon.