For the average PC, most of its noise comes from its fans. Computers are typically built with cooling fans that are meant to operate at acceptable noise levels. Although, as machines age, they tend to require more work out of the installed fans in order to keep the components cool, which may explain why your old machine is much louder today than when you first got it. Also, if you’ve not cleaned out your PC recently, then you may be surprised to find that it’s accumulated a significant amount of dust. All of this dust can build up on the fans and other components, causing the fans to work harder and create more noise. If you’ve got a dirty computer, then you may find that a good cleaning wil...