FPS Capped

Hello, recently my fps was really low (on the higher waves) and I searched on several forums and a solution was to untick "Reduce Mouse Lag" so I did that. Fps was a bit more decent (mind you, i use a 9800gtx+) But recently, I had been getting a capped FPS of 48, I restarted by steam, then my Fps was capped at 85. I have no idea why, it just used to flucuate (I perfer that) from 40-200. My display setting don't have v-sync ticked. I also used Nvidia Control Panel, dont know if that has anything to do with it. (I would think it is the control panel)

Any Solutions?

Thanks