Strange whining sound

Hi,



Newbie here. I've run into a bit of a problem overnight. My monitors immediately hum/whine when I turn my computer on. They weren't doing this yesterday. The monitors are plugged into a different surge protected plug gangway to the surge protected plug gangway the computer is plugged into.



I run a very basic system and as far as I can tell, noting has changed overnight other than this noise.



Thanks for your help in advance.