Bull hockey pucks!
I installed these over the weekend for my 4870X2. My "Windows Experience rating" went from 5.9 (with my graphics at 7.9 and my hard drive at 5.9) to 4.5 specifically because of my graphics. (Everything else stayed the same, processor at 7.9, disk at 5.9, memory at 7.9.) My Aero graphics went from 7.9 down to 4.5. my 3D graphics went from 7.9 to 5.7.
Going in to actual games, World of Warcraft seems mostly unaffected, unless I turn my AA up to 8X. Where before I would get 25-30 in a crowded Dalaran with 8XAA, now I get 5-15. At 2XAA, I still get 55-60.
With Diablo II, it is unplayable at 2-3 fps. It would at least work before, but not any longer. With Starfleet Command, I get a constant flicker on the screen, but this started with 10.1.
With virtual machines, the performance went through the floor.
It's like it won't go up to normal operating frequency and stays at the "idle" clock speeds or 500/500.
I'm going back to 9.12. all the 10's so far have been bad for my 4870X2.