BIOS FLASH GRAPHICS CARD

This is VERY risky. Check the board design first, but usually this is a no-no, UNLESS you have a way to recover the bios (blind flash or 2nd video adapter in the same computer and so on). The chips used on the ASUS are likely higher binned, especially the memory. This means that even if the BIOS is compatible because the board designs are the same (unlikely, since ASUS usually does non-reference custom designs), the BIOS flash will result in a non-usable card possibly damaging it.

You COULD use RBE (Radeon Bios Editor):

http://www.techpowerup.com/rbe/

To customize your BIOS, but be aware, the fan speeds are no longer controlled by the Bios profile once the driver is loaded for ATI cards since a few years ago. So if you over heat, you'll have to find another way to manually adjust fan speed or do something about it.

To the best of my knowledge, if the card has issues in the future, you'll need to undo the bios flash (so save a back up of the old bios file) if you want to RMA with XFX.