The GPU I have is weird. It has 2 BIOSES that you switch. Its the 6990 which is 2 cores. Its very loud and power hungry.
I think in the past I flashed the wrong bios when undervolting. This time I flashed the 2nd BIOS (the OC one) and windows finally seems to boot.
Huge difference. The fan is SILENT!
Temperatures are much better at 70C instead of running at 90C and peaking at 100C.
Most of them do now a days sense you figured it out i would use bios 2 i think that's one that lets you OC or does on my 280 my 290 is unlocked out of the box . .I only OC mine for gaming sense to me it seems to cost about the same to buy a few sha256 miner till some one comes out with a cheap more efficient miner then the A2 or titan then I'll buy some of them that might not happen till the end of year if then .