I don't like the term bottlenecking. Games need a certain amount of CPU power to hit a certain framerate. A GPU determines what graphical settings you can run, but will not increase your max framerate. By changing the graphical settings, you can shift the "bottleneck", or limiting factor, back and forth between CPU and GPU.
A more useful question to ask is, "Can my CPU deliver the framerates I want in the games I play?"