Try running a scan with Malwarebytes. If there is anything malicious this should find it.
In addition to this, make sure that your system is not defaulting to your integrated GPU. Open device manager (Windows key + R, then type devmgmt.msc and press ok). Then click monitors, right click your display and press properties. If your location says something like "on Intel(R) HD Graphics Family" than your PC is not using the correct adapter.
If you are still having problems, completely uninstall all GeForce or Radeon drivers (including Geforce experience and Raptr etc) on the system, restart and then install only the newest copy of Nvidias drivers, do this directly from Nvidias website rather than Windows Update or Geforce experience. As of posting this is the correct location. Select your specific windows version on the right hand side and download the latest driver. If you still have issues, you can try beta drivers here.