Ok so I decided to test my MSI 970 in my partners pc with a 600w OCZ psu and the coil whine was even worse and even comes through the speakers. I even tested it on an old pc power and cooling silencer 610w and is just as bad so its def not the psu. Have gone for an RMA now so hopefully the replacement won't have the same issue. Back to 660sli for now I guess.