Being quite electro-mechanically minded I'm pretty good at tracking down odd pc sounds.
For example my pc was making a very odd sound on boot up not long ago, i traced it down to a noisy fan, pulled the fan apart, greased it and put it back together and my pc is nice and quiet again.
__________________
"If at first you do not succeed, sit down, have a coffee, have a smoke, and think for a bit. If that still doesn't work, post it on TST".