On some computers the display appears to flicker or shimmer. This is due to a low "refresh rate".
A refresh rate is the measurement of how many times, per second, that a screen is redrawn (or refreshed). This
is rather like the frames per second measurement of films. However, due to a computer's screen being drawn by a
dot of light as opposed to a complete picture being shown all at once, this rate needs to be faster than a film's
frames per second to be unnoticed by the human eye.
By default, a computer with a Windows ™ operating system (OS), will set this at 60 Hz (60 times per second) if
the monitor make and model are unknown to Windows. The minimum "refresh rate" recommended by the EU (and
elsewhere) for a standard computer is 72 Hz. For a monitor larger than 14" diagonal measurement, 75Hz or more
is a more appropriate setting.
Setting a refresh rate which is higher than the capability
of your monitor can damage it.
If you have installed your monitor correctly the danger
should not arise. The maximum rates for your monitor vary according to the resolution and the OS is automatically
informed of those rates by your monitor (if Plug & Play) and by its driver (INF file). This should ensure that
the OS will not provide rates which are too high for your monitor. To be safe, check that your monitor (and specific
model) is shown correctly in the Display Properties window discussed below.
Adjusting the Rate
The commonest OS for a domestic PC is standard Windows (typically 95, 98 or ME). Windows NT (the business version)
looks almost identical but gives a far greater control to system administrators. Therefore it may not be possible
to access the necessary controls to change the refresh rate without IT involvement. For computers where adjustment
is both necessary and possible, here is a description of how to accomplish the change in most cases.