Sadly, flashing the BIOS can't do squat! It's not like the GeForce GTX 660 Ti that was given to me, where my buddy, the previous owner, went ahead and flashed a BIOS from a different vendor.
A BIOS flash will only help in a situation where 3D is in some whacked power state and has phantom TDP throttling.
My buddy went ahead and flashed an Asus video BIOS to an eVGA GeForce video card and caused all or most 3D programs to be throttled with false reports of the TDP being exceeded.
Unigine Heaven would keep stuttering. It also caused apparent undervolting that cause random "Display driver stopped responding and recovered" (or similar) Windows errors.
After flashing an eVGA video BIOS, all the problems were gone! I got real lucky! I was beginning to think that my card was bad.
Unlike my case, your problem sounds like straight-up bad hardware!