Any chance your V-Sync is turned on (in Nvidia and/or in-game)? This caps the FPS to such ~60 frames on a 60Hz monitor. But, no point in going over 60fps if indeed your monitor can only display 60 due to the refresh rate.
If VSync is already off, you can also try setting the Compatibility mode (to other windows version) such as shown here:
https://www.youtube.com/watch?v=VoEOsUpsawQ
If you're using Windows 10 and DVR (Xbox app), try disabling that: https://steamcommunity.com/app/730/discussions/0/617336568081303155/
You can also set the power option settings to prefer max. performance: https://www.reddit.com/r/nvidia/comments/2twn8z/nvidia_please_disable_the_adaptive_power/