CPU bottleneck somehow "synchronizes" frames, because GPUs have to wait for next frame.
Wors scenario of MS is in CoJ, which is completly unplayable below 70 FPS.
GRID is completly unplayable below 40 FPS and at 50 FPS you can see it starts to slow down.
Crysis is quite OK at 40 FPS with CF because of motion blur.
Today I'll end tests of 3850 CF and in next week I'll type this article.
I have no idea how does it look like in 4870X2, because I still don't have one, but I hope I'll have one soon for tests