If it's an old CRT monitor there's some relays inside the monitor that 'click' when activated and that's usually when you make changes to the video adapter such as resolution or refresh rate. Possibly it's having a problem maintaining the settings it's at now. You may check to see if you can change those settings to something more basic.
The clicking could also be arcing due to a bad part. If that's the case I wouldn't expect the monitor to last much longer.
Again, if it's an old CRT type you can get arcing due to dust build up. However I wouldn't recommend looking inside due to dangerous voltages that persist even if turned off and unplugged. Is there a "sweet" smell coming from the monitor because that is caused by the ozone produced due to arcing.
If it's an LCD monitor forget all I've said.
Always pop back and let us know the outcome - thanks
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