Some info on monitors...
I've been told that repeatedly turning off your monitor can reduce the lifespan of your monitor.
I only turn it off once a day and that's when I go to bed. As an alternative you could go into screensavers choose blank screensaver and choose preview.
You can set the monitor to turn off after a certain period of time. Minimum 1 minute, but my comp didnt' like this for some reason. monitor would just turn off and on again right away. *shrugs*
As for that noise your comp is emitting, try increasing your refresh rate. Try to find out what the recommended is from your manufacturer and change it to those settings.
Control Panel>Display Properties>settings> Monitor>Screen refersh rate.
Let Windows Hide fields you can't support, and then choose highest for your resolution.
Mine is set to 1024x768 at a refresh rate of 85.