The higher the refresh rate, the clearer the image appears on the screen. At lower refresh rates like 60hz your eyes can see the screen refreshing so it appears to kinda flicker. Try it, set your monitor at a resolution with a high refresh rate then turn it to a lower refresh rate. To really notive it, look at something right next to your monitor while you have it on a low refresh rate and you will see the image flickering much more in the corner of your eye. Then turn the refresh rate back up and look tot he side, and you won't see it flickering. It's noticeable...and hurts me eyes after a while.