Whenever I turn my computer on, somewhere around the cpu starts buzzing extremely loud, to where I can hear it slightly from 1 floor down. I've checked the gpu, hdd, and power supply and think I have narrowed it down to the cpu or the cpu fan. When I stop the fan with my finger, the noise instantly stops, but will sometimes continue a couple seconds later when I still am holding the fan. Also, the noise happens a lot less frequently when I put it on its side, rather than having it standing up. This noise has been going on for about a month and a half now. I haven't experienced anything wrong when I am using the computer. The noise still occurs, but the computer functions normally when I use it.