What’s a monitor refresh rate? And what does it do?
That’s a multifaceted question, but here we go.

The “Vertical Refresh Rate” is the number of times a second that the video is displayed on the CRT monitor. (On LCD monitors, a vertical refresh is a fixed rate, and does not change…) Older CRT monitors could be damaged by setting the Refresh rate too high or too low, but this is virtually unheard of now, since any monitor in the last 10 years (or so) should auto-detect a bad signal and just display a message (eg. No video signal).

This refresh rate is caused by the fact that the electron beam used to “paint” the image, also causes the display to illuminate.

For CRT monitors, a low refresh rate may cause the display to switch to interlace video mode. Interlaced video, can cause eye strain and headaches for some people, as well as a slightly degraded image.

What is interlaced video?

First, let’s define, non-interlaced video… Non-interlaced video, is when the display simply draws the entire frame of video all at once. Starting from line #0 and stopping at the bottom of the picture.

A interlaced video, is when the display paints every other line (eg Odd Lines), and then comes back up, and paints in the other set (eg, Even lines). Due to the persistence of vision, it appears that everything is drawn at the same time, but it isn’t.

For static images, this isn’t too taxing, but for objects in motion…

If you look closely at the right side of the man’s head, you will notice a series of horizontal lines. These horizontal lines are an artifact of interlacing. This is often referred to as the combing effect because the lines look like the teeth of a hair comb.

The even lines in this picture, which are what you see on the right side of the man’s head, make up the even field of the video. The odd lines, which you can see on the left of his head, make up the odd field. In this picture, the man is turning his head to the right.

For comfortable viewing, use a refresh rate of 70Hz or higher. To change this setting in Windows XP, right-click on the desktop, and then choose Properties. Click the “Settings” tab, and then click “Advanced”. Under the “Monitor” tab, lies the screen refresh rate options.

On the Macintosh, Go to System Preferences –> Displays. Under the Display tab, you may have a option called “Refresh rate”. If you don’t, then you don’t need to worry about it. If you do, feel free to change it to 70 Hertz or higher…

The key here to find a value that you are comfortable with.