Have you tried flashing on the 6970 BIOS for unlocking more shaders, too?

6950 specific
I do not recommend using the 6970 firmware. Instead use your original firmware, but modified with the "shaders unlock" patch. There have been several reports of permanent damage, probably because of the different voltage and timings used in the 6970 firmware. It will also make the card use more power, which means higher cost and quite a lot more noise from the fan.