Having frame rate issues with GTX 660 Ti

What is your monitor refresh rate?

its 60hz which is pretty bad.

Yes you monitor will bottleneck and you see no difference anything above 60fps.have you turned the vsync to on?it is must.

Try to completely reinstall the drivers

Vsync is something that a lot of cs players don't use. It screws up the 1:1 mouse ratio to monitor, making it very hard to have a consistent shot. I was wondering if this issue would be solved if I tried overclock my video card? Is that a feasble solution?

You have to use vsync.whenever fps is more than the refresh rate vsync is must.

First of all, it seems to be a problem with drivers.

Also, you can't see above 60FPS so there really is nothing to worry about.

make sure your mb bios is up to date..there been a lot of patches for the z77 mb and cpu/ram/video cards.

most gpu frame rate drops like yours may be from the gpu getting to hot. a lot of times the stock firmware on the gpu and the video drivers dont turn the fans up to max speed as the gpu card temps ramp up. i would try msi afterburner and try some fan ramps. fine a balance between frame rates and fan speed/noise. also check with cpu z that your ram running at it max speed. a lot of new builds forget to turn on xmp profile in there bios and there ram running at 1333 speed. also there a trade off between eye candy and frame rates. fxaa and anti lasting..the higher those are the more gpu works..lower the frame rate goes on some cards and games. also look to see if the game is/was written for dx9 or dx10 and see what mode it running in.