mgoldfinger, would you be able to disclose what BIOS you've flashed too and/or where you obtained it?
I found this thread after Googling a bit and I'm having the exact same problem: fresh build, fresh Win7 64 install, (single) XFX HD 7950 DD has ever increasing HW failures at difficulty 13+ (it also rises in temperature pretty quickly after as well). Everything is stock. I've yet to toy with TC values.
GPU-Z lists the current BIOS as 015.024.000.001.000000
Glad you got yours working!