No, first thing is reducing voltage. No need to edit bios for that.
Too late
I flashed 1 gpu using ubermix 3.1 straps (it is a samsung memory)
After that MB won't boot with HDMI connected to it, however it is still being recongnized in windows and capable to mine.
I flashed back its original BIOS, however the display was not fixed.
It is still on warranty so I will return the card.
EDIT:
Apparently the backed up ROM extracted from gpu-z of that card was invalid, and the strap modification I did it on that ROM. Good thing is, I did a backup of all ROM so I could reestablish it and its working
As a rule of thumb never use GPUZ to save roms. Use the bios flashing utility itself.