I've had my pc for a little less than four months now and it has been real quiet. Today suddenly it started making this constant high pitched noise. So I thought it must be a fan.

I opened up the case to listen where the sound is coming from and it sounded like it was definitely in the front. So I've got a fan in the front and also my hard drive. I switched off the pc and removed the fan's power and turned it on again and the sound was still there.

Can it be my hard drive? It's a Seagate 500Gb. I'm going to download some programs to test it now, but it looks like it's fine.