Hi all i recently bought a second hand dell dimension 5000 from a shop and when i got it home i noticed that when i start doing anything on it it starts to get really dam noisey and on the odd occasion when i have been using it for a while i have to reboot my pc to get the noise to stop. It sounds like its about to take off and getting on my nerves now.

I have taken the side off and cleaned the power fan and as much as i can get to but that has not made any difference.

Can anyone help me please??