Look in your drivers settings, you should have a "wait for vsynch" option. When it is checked, the framerate adapts to the frequency of your monitor (80 in your case), if it is unchecked, the framerate goes the higher it can.
Do you have an LCD screen (with VSync enabled)? 60Hz on a CRT monitor would give me a headache in less than a couple minutes, though some people are not as sensitive to screen flicker.
anyway, your FPS is physically limited to your refresh rate as your monitor only shows the amount of images a second as your refresh reguardless of your FPS, and a reresh less then 70 may cause eventual blindness.
As far as refreshrate i heard that befor,but my oneline game planetside fpses are allways changing do to the invierment. I'll get 100 fps in sanc and as low as 30fps in heavy zerg.