You will need
  • For cleaning and lubrication of fans, you need to stock up on a few grams of motor oil, Phillips screwdriver and a fair amount of patience.
You must first check the correct settings of the fan speed in the BIOS. It is often possible to deal with the fact that the CPU fan is configured for continuous rotation with maximum speed, even if it is the radiator completely cold and CPU is not loaded with work. This excess noise from the rotation, which does not bear absolutely no use to your computer. When the computer boots, press the "Delete" button. Loaded BIOS. Look for the option "Smart fun control". In order for the fans not spinning in vain at maximum speed — this parameter must be enabled.
Check up reliability of fastening of all nodes in the system unit to its corps. Tighten the bolts hard drives, power supply, cover of the system unit. Sometimes loose the device are the source of the noise.
If after adjustment the noise is not gone — apparently the fans are choked with dust, or barely any grease.
Completely power off the computer. Remove the left side cover of the system unit. Often to do this, Unscrew the two screws located on the rear panel of the system unit.

Determine the source of noise is the CPU fan or power supply fan makes most of the noise?
In the first case, you can do a partial disassembly. Put the system unit on its side. Without removing the fan, remove the sticker on the top. Apply one or two drops of machine oil on the bearing of the cooler. Try not to get oil place of sticking the stickers back otherwise you can glue it will be difficult. After that, stick the sticker onto the place.
For the lubrication of power supply fan — you need to remove it. Unplug it from the computer. Unscrew the four mounting bolts from the housing of the system unit. Remove the power supply. Loosen the bolts it covers. Remove it. Now Unscrew the bolts of the fan. In the same way as in the case of the processor fan, remove the sticker. If the bearing is closed with rubber cover — gently remove it. Drip a few drops of oil. Assemble the power supply and connect it to the system unit in the reverse order.