CRT, or Cathode Ray Tube monitors, though differing from televisions in several respects, share one important characteristic. Like TVs, the picture you see is constantly being redrawn on the screen. This refreshing action is the cause of the almost imperceptible flicker seen in the typical computer monitor image.
Now, the slower the monitor refreshes itself, the more perceptible this flicker is, and the more perceptible the flickering is, the more likely you are to suffer from eyestrain, headaches and general fatigue as a result of it. Windows XP defaults to a refresh rate of just 60Hz, meaning that the screen redraws itself 60 times a second. This is pretty much the lowest acceptable rate, and higher refresh settings can have a considerable positive effect on computer experience.
Note that refresh settings are limited to a certain degree by the capabilities of your video card, and to a much greater degree by the capabilities of your monitor.
Every monitor has a maximum refresh rate it is capable of displaying at a given resolution (for example, a typical 17-inch monitor of a few years ago will happily crank out 85Hz or more at a resolution of 800×600, but may only be capable of 60Hz at 1600×1200).
If this refresh rate is exceeded, the image will be distorted and unusable.
Older CRT monitors, especially 15-inch or smaller ones, tend not to be capable of a refresh rate much over 60Hz, especially at resolutions greater than 640X480. Also, setting the refresh rate does not have the same effect on LCD or flat panel monitors, as their screens are not redrawn in the same way.
To change your monitor refresh rate follow this procedure
Right click on an empty space on your desktop (no icons) and select ‘properties.
Click the ‘settings’ tab and choose the ‘advanced’ button.
Now choose the ‘adaptor’ tab and click the ‘show all modes’ button.
This presents you with a list of resolution, colour and refresh rate options that your video card\monitor combination is capable of displaying. You can experiment with these settings by using the ‘apply’ button. Note that a refresh rate of 75Hz or above is generally recommended, (keep in mind most monitors do not support settings higher than 85Hz).
After you set the refresh rate, you may feel a little uncomfortable for a short while as your eyes adjust, but rest assured you will grow to appreciate the difference in ease of viewing.