^Yes, but AC mains frequency has nothing to do with it, WarraWarra
. People in countries with 50 Hz mains could still be running their monitor at 50 Hz, 59 Hz, 60 Hz, 70 Hz etc. It depends on the monitor and screen resolution one is using, not the mains frequency.
What can cause nasty effects on a monitor, whatever the mains frequency, is if the mains is dirty (electrical noise), in which case a mains filter/smoother is helpful: http://www.steinmusic.de/netzeng.htm