Flanker, yes, a CPU CAN bottleneck a graphics card.
my CPU bottlenecks my GPU a lot of the time (Athlon XP 2800+)
it depends on how much physics, AI and whatever is in the game.
if I play Generals against several hard enemies (yes I still play Generals) then the CPU has to deal with a lot of AI (the hard enemies build and control lots of stuff) and it DOES bottleneck my GPU, which by the way isn't extremely powerful itself (an FX-5200)
if I play against one easy enemy (I sometimes did when I first started playing) it doesn't have to deal with much, and the game goes much faster. and that's with the same level of graphics.
the FX-57, although it is very powerful, can and sometimes does bottleneck a GPU. although it would be moree so on higher-end GPU's, such as the 7800's