In order to change your refresh rate, you go to display properties (right click on desktop, properties) - go to the "settings" tab - click on "Advanced" - look for the monitor tab - set the refresh rate to 85 Hertz. Happy Su-lin.
If that doesn't work, you can try re-installing your graphics driver - www.nvidia.com if I remember your family computer correctly.
It'll be much better for you eyes.
