Originally Posted by Aquinus
No one has done is successfully because they're two very different cards with different voltages and hardware on the inside. It should never work for any 6850. Anyone who said that they did are lying to you.
You can keep playing with it, but I think the damage has been done.
Pretty sure he is lying or flashed a different BIOS than the thought, because every time someone does this on TPU, it fails like yours did. In fact other people are worse off because their card doesn't even get detected after doing this. You're better off than most.
Lesson learned, I read the details on the BIOS download page, the clock speeds and voltages for the 6870 BIOS were what I was running my card at using MSI AB anyway, but naively neglected to check what the rest of the card was running at
I didn't expect to convert a 6850 into a 6870, just do away with the need for software to OC it