I have done this on my X800pro VIVO and it unlocked all the pipelines.
Now have all 16 at X800XT speed.......it wont go to ful XTPE speed without a voltage mod.Some lucky people got cards that would unlock to full XTPE spec...but I'm more than happy with the results I got on my card.
I believe some of the later cards were laser cut and so the extra pipelines could not be unlocked.
Of course you have the X850pro which might make things different,but I believe it is possible.
Instructions click here