Over the past 2 days my pc has decided to frequantly shut itself off while in windows. At first I thought it might be my graphics card so i decded to update all of my drives. When the problem continued I decided it my be the computer overheating So i removed the heatsink and blew out the dust using compressed air(lots of dust). I replaced the heatsink but now the computer is refusing to boot. It starts normally and detects the Hdisk etc. Then a funny noise high pitched squeal begins and it refuses to go past the RAID page. I cannot access the bios without the computer turning itself off either. It just powers out but leaves a red light on the hardisk. All the fans etc turn themselfs off. The computer is 3.2 pent 4 Aopen S66FXM -7s. Obsiouly I have caused a problem somwhere and im guessng its hardware related ne ideas ?

Is the high pitched squeal comming from the PC speaker or it sounds more like some mechanical parts make it?

Make sure that the heat sink is installed properly and that the CPU fan is connected to the motherboard.

Check your power supply, because that may be causing issues with restarting as well.

Also try to boot with only required devices - unplug all unnecessary fans, disconnect cd-roms, unplug all devices but video card (and the RAID controller) and then try booting up again.