I think they have the same Pinout, but im not sure. You could measure the Pins with a DMM and compare.
These Links should help you.
MSI GTX570 TFIII PE hardmod - Page 2
MSI 6950 TFIII PE/OC- testing w/ CL3P20
Hey i just desoldered the powersection of a 8800gts 512 to get a powerboard on it.
I measured the resistance of the vGPU points and there were just 0.5-0.6Ohm.
Is this still ok or do you think i shorted something?
I heard under 0.5Ohm its mostly a short.