What does "check system fan" mean?

Home » Hardware

Summary: Your system fan is an important component of your system. If the fan fails your system could fail or some components could even be damaged.

Don't get me wrong, I'm not trying to be curt, but the message means exactly what it says: you need to check the fan in your system.

What fan? What's a fan? Which fan? And why?

Fair enough, let's review one of the most under-appreciated components of your system.

•

Almost every computer has one or more fans that blow air through the inside of the computer case. This is true for laptops as well as desktops. In fact, the system fan is a critical component. If the fan fails your computer may overheat and damage other critical components.

There may be more than one fan.

For desktop machines there's typically at least one fan in or near the power supply. The power supply itself can generate a fair amount of heat, and having a fan nearby not only keeps it cool, but also ends up moving air through the rest of your computer's enclosure.

There may sometimes be a second fan near the front of the computer, just behind the faceplate. This fan, in conjunction with the fan at the back of the computer, helps to keep air moving through the computer. One will push air in, and the other will pull air out.

In some cases there's yet another fan, directly on or over the CPU. The CPU is another source of a great deal of heat. Placing a fan near the CPU itself keeps cooler air blowing over it to help dissipate some of that generated heat.

•

As I said, the system fan is a critical component. So critical, in fact, that in recent years additional circuitry has been added to computers to allow the computer to monitor the fan and make sure it's working properly.

So, which fan?

On this there's no standard that I'm aware of.

My recommendation: check them all. If your system is failing to boot because of a problem with one or more of its fans, it's important to check it out. You'll need to open the case and see which one isn't working. If you're not comfortable doing that, particularly if you have a laptop, then you'll need to take your machine to a technician for diagnosis.

Related:

• Ask Leo! - My upgraded computer keeps shutting down - what should I do?

• Ask Leo! - My computer locks up and won't boot. What do I do?

Article 11613 | Posted July 2, 2007