If your existing fan is making noise or sounds as if it's laboring, you need to replace it. Also, if you do not hear anything when you turn your computer on, chances are your fan has quit working.

Here are some facts that might help you reduce the noise of your computer:
1. The more airflow within your computer - the more noise.
2. Obstructions along the path of the airflow will create noise.
3. The higher speed fan will generate greater noise than a lower speed fan.
4. A larger size fan will generate lower noise level than a smaller size fan for the same amount of airflow.
5. The higher voltage applied to the fan will generate higher noise level.
6. Fan design can reduce noise level therefore users should choose reliable fans to avoid excessive noise.

A system fan is a fan that will cool the entire computer system. Although it will not cool specific components within the computer case it will keep air moving throughout your computer case. In an effort to be competitive, many of the computer manufacturers keep their costs low by only having an exhaust fan at the power supply. In the new era of GHz these exhaust fans do little to keep the inside of your computer cool, let alone the specific component such as the VGA video ccard or hard drive.