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Processors Toolkit

Fix noisy computer fans with a drop of oil

Greg Shultz Tech Republic

Published: 03 Jun 2003 11:01 BST

How do computer cooling fans work?
Almost all computer-cooling fans are designed around a sleeve bearing assembly -- although I have encountered some computer cooling fans that use a ball bearing assembly. For this article, I'll focus on the sleeve bearing assembly.

A sleeve bearing assembly is composed of a shaft (to which the fan blade is attached) that rotates inside of a stationary cylinder. In this case, the cylinder is made of a porous metal, which is impregnated with oil. As the shaft rotates, oil is pulled out of the cylinder creating a film of oil on which the shaft rides. This film of oil prevents metal-to-metal contact and thereby eliminates friction and almost all noise. This type of sleeve bearing assembly is illustrated in Figure A.

Figure A

A sleeve bearing assembly is composed of a shaft that rotates inside of a stationary cylinder.

In a perfect sleeve bearing assembly, the amount of oil in the bearing is the correct amount and stays constant throughout the life of the fan. However, if the assembly doesn't stay sealed properly, some of the oil can dry up over time. When that happens, the rotating shaft will come in direct contact with the stationary cylinder, which creates a scraping or grinding sound.

In addition to the noise, the increased friction will cause the fan to rotate slower, which in turn will reduce the airflow. If the airflow is reduced, the system will run hotter than it should, which puts certain components at risk for failure. Replenishing the oil reserve in the sleeve bearing assembly will reverse this condition.

Does your PC have a fever?
If you want to monitor the temperature inside your PC, you might want to investigate software like CompuNurse or a Lian Li LCD Thermometer.

Oiling the fan
Now comes the tricky part. How exactly do you go about oiling a computer-cooling fan that uses a sleeve bearing assembly? Well, to begin with, you need to use only a single drop of oil.

If you refer to Figure A, you'll see that the lubrication point is located in the centre of the fan. It's a good rule of thumb to physically remove the fan from the computer to oil it.