Ok, so I spent many hours last night trying to do the unlock. Here is what I did
1) First I did the chewing gum mod (
http://hardforum.com/showthread.php?p=1037522585) but adapted to the Gigabyte 6950 (
http://www.techpowerup.com/forums/showthread.php?t=148806).
2) The gum mod worked and allowed me to write to the bios
3) Used GPU-z to save stock bios image
4) Used RBE to edit the bios and unlock extra cores
5) Flashed bios back to the card
6) Rebooted
7) Result= no change in number of shaders
Tried again with Wizzard's script for modding the bios image, also no success
After reading in some other forums it appears that ATI/AMD have gotten annoyed that users can reflash and unlock more shaders. Thus, they have started to laser cut connections to the extra shaders on the die, making it impossible to unlock. This appears to apply to all recent dies.
I am running Ubuntu 11.04 for my mining rigs, but RBE is window only so I took a spare drive and installed Windows 7 to do this. Tools used were GPU-z, Radeon BIOS Editor (RBE), ATIwinFlash, and Wizzard's mod script (sometimes works better than RBE)