A computer fan is any fan inside a computer case. Their purpose is cooling. They might work by drawing cooler outside air into the case, or they may expel heated air from the inside. They might also blow air across a heat sink. Regardless, the cooling of the components of a computer is essential. Computers do not generate massive amounts of heat, but the increasingly rapid processing units do generate some, and unless cooling takes place, trouble will surely follow.

A heat sink is an environment or object with a lower heat capacity than the surrounding area or adjacent component. Heat will be drawn from the targeted area into the heat sink by thermal transfer. This is the concept of Thermal Equilibrium. It is why a window pane will feel cold to the touch. What actually happens is that heat flows from your finger to the cooler glass. The fans inside the computer blow air over the heat sink to dissipate the heat.

Fan problems can be divided into two groups. First, they cease to run, and second they can make excessive noise. The problems are related. A computer fan is just a normal simple fan that runs on bearings. When the bearing begins to go bad, or the fan gets out of alignment, it makes noise. When the bearings go bad, it stops running.

There can be several fans inside the computer. There is one connected with the power supply, one cooling the inside of the case, and one specifically cooling the CPU. When the problem is noise, the first step is isolating the fan that has the problem. The only other mechanical component inside the case that might be making noise is the hard drive itself. This is, of course, a totally separate problem. So, it is important to determine that the source of the noise is a fan, and then determine exactly which one. One suggestion is to stick the end of a paper clip into the fan blades for a few seconds stopping the rotation. If the noise stops as well, you have your culprit. Normally, however, you can locate the problem with just your ears.

The fans can be oiled. WD-40 is not recommended here because it is designed to remove moisture, and that is not the problem. Any light weight oil is good. A popular choice is 3 in 1 oil, although many experts tend to prefer sewing machine oil. If the oil works, you still should be aware that most likely this is only a temporary fix. The noise was trying to tell you something about the condition of the fan, and silencing it did not address that condition. In the end, replacement of the fan is going to be the permanent solution. The fans seem like minor little mechanical asides in the vast overall picture of hard drives and micro processors, but cooling is essential. You should give serious attention to the proper operation of fans. The true fan problems are what happen to your computer when they do not work properly.