CRT monitors may flicker but it depends on the refresh rate and the type of lights in the room that the monitor is in. If you are running flourescents, they will cycle at 50Hz or 60Hz depending on where you are. If your monitor is set to the same rate, you will see massive flicker. If your monitor is close, but not quite the same, then you will see flicker on occasion. Usually when the image is moving fast. CRT's have had refresh rates as high as 120Hz or more which means you won't see the flicker no matter what happens on the screen.