Flicker

Flicker in cathode ray tube (CRT) monitors results either from a too-low "refresh rate," from a failing monitor or video card, or from electromagnetic interference.

Refresh Rate

Your brain creates the image you see on your monitor's screen by blending fast-flashing, strobe-like images that appear so quickly that they merge into one continuous image. The term "refresh rate" refers to the number of times a second the image on the screen changes. Typically, Windows sets the refresh rate at 60 "flashes" a second. When the refresh rate drops, or is set, below 60---and for some people even at 60---the flashes occur slowly enough that your mind can differentiate between the flickers, and you "see" them.

Check the refresh rate set for your monitor. If your computer has selected a refresh rate of 60 or above, you should not see a flickering screen. If the computer has set its refresh rate below 60, manually changing it to a higher setting should solve the problem.

Get the Latest Drivers

If manually increasing the refresh rate doesn't solve the flickering problem, make sure you have the latest drivers for both your graphics card and your monitor. If upgrading drivers doesn't solve the problem, consider changing out your video card. However, don't spend money on a new video card until you've at tried the solutions discussed below.

Try Another Computer

If the monitor continues to flash with the latest drivers installed, attach your monitor to a different computer, one in a different location than your computer (in another part of your home or apartment, if possible). If your monitor continues to flicker, the problem is in your monitor. Consider replacing your older CRT monitor with a new monitor based on technologies that don't suffer from "flashing" issues.

If your monitor doesn't flicker, you can assume the problem is either interference or in your computer.

Eliminate Interference

To rule out interference, reattach your monitor to your computer. Before you boot, make sure to move or turn off every piece of equipment within 15 or 20 feet of your computer. Everything includes such things as powered speakers (or bass unit), powered telephones (i.e. phone/answering machines), printers, fax machines, external drives and even the ceiling fan--everything except your computer and your monitor. Boot your computer.

If the monitor doesn't flash, electrical interference is the problem. With your computer running, turn back the un-powered equipment on one unit at a time. Obviously, when the screen starts flickering again, you've found the unit that is interfering. Relocate the leaky electronics away from your computer.

If none of the above work, consider replacing your video card. If that doesn't work, bite the bullet and buy a new monitor.