Alternatively referred to as frame rate, horizontal scan rate, vertical frequency, or frequency. Refresh rate is a CRT monitor measurement in Hz that indicates how many times per second a monitor screen image is renewed. For example, a monitor with a refresh rate to 75 Hz means the screen is going to redraw 75 times per second.
Refresh rates below 75 Hz can produce an often imperceptible flicker that can cause eyestrain after long viewing. While some cards can support as high as 120 Hz, sometimes even higher, it is recommended you run 85-90 Hz; rates beyond 90 Hz add an unnecessary processing burden to the eyes. Finally, an LCD does not have a refresh rate; however, if you need to set a rate, values of 40 Hz or 60 Hz can be used.