If electrolytic capacitors are not swollen, and when measuring with a multimeter show normal resistance, what is the reason they are not fit
To test the capacitors you'll need an ESR meter.
In my experience, replacing the filter capacitors in the switch mode power supply of an LCD monitor solves about half of the problems with them.
It's a cheap and easy fix, and my experience with Acer monitors is that it's not "if", but "when".
If you don't want to replace them straight away, try soldering some new caps temporarily in parallel with the existing ones. The only problem with this is that you then may have to operate the monitor with the power supply removed and exposed and this may be dangerous.