not at all, but for some reason people think that the cpu bottle necks the gpu a lot, which it doesnt. all the cpu has to do is send it commands, that are just a couple MB in size, since most cards already have all the stuff cached, the cpu only has to send the textures\models\animations\etc. during the loading screen.
once you get down to a much lower end cpu, then yeah it will bottle neck it a little. for example i have a 3600+ X2, running 2 cores @ 1.9ghz, brisbane core.
stock 3dMark06 with 8800GTS 320 was around 8000
oced from 1.9 to 2.5, my score was about 8600, 99% coming from the boosted cpu score