CrazeD said:60Hz is the refresh rate for the monitor. I don't see how that would lower or limit your FPS, though.
Most games have a cap on FPS. Why I am not sure.
That cap is there to prevent your FPS jumping to 200 and down to 30-60fps, that would cause the game to become VERY jumpy, so they cap it to 80-120fps usualy [mine for example is capped for 120fps] so the jumps downwards won't be so dramatical..
-Jo