When I play some games, it will make the sound. It quickly fades in, makes the sound for a few seconds, and then fades out into nothing. Then there is silence for 10-20 seconds and it then makes the noise again.
It sounds like a light bulb when it is about to die out. There are 3 blue lights at the bottom of the case, and 1 of them is broken.
The noise only comes when I play either 'Fallout 3', 'Oblivion' with a shader mod (noise doesn't come when that mod isn't enabled) and 'Crysis'.
I can't really figure out why this noise comes.. any ideas?