PSU Making A High Pitched Noise

[Austinstr1]

A few days ago my PSU started making a high pitched noise everytime I turn my computer off. When it is running I don't hear it at all. But when I turn off my computer that's when I hear it. So then I decided to switch the PSU switch to off and the high pitched noise went away. Have had it a little over a month now. Is it something I should worry about? It's a Cooler Master 700 watt PSU and used for gaming. For about 2-4 weeks it would run for about 8 to 12 hours, but for the past few days now school has started back up and I would say I am on it less than 2 hours a week. I was a hardcore gamer when their was no school. So is it something I should worry about and get it replaced?

 

[Dark Lord of Tech]

What model Cooler Master?