Managed to find a thread on WOW forum as they are having the same problems and one person is a tester for amd and mentions that there is a problem with x58 and x79 chipsets combined with high end amd 7000 series cards and that amd are aware of the problem. They have managed to replicate it and are working on a fix. So sounds driver related. WOW guys fixed for now by going dx9 but blops 2 only supports dx11.