If you have a desktop computer then the main place dust accumulates is around the CPU unit and fan areas. To prevent your processor from over heating there is a fan connected to a heat sink which sits on top of the processor to disperse the heat. This fan blows air down on to the heat sink to cool it down as the heat is passed up from the CPU. Because the fan is constantly blowing air it also blows the dust particles in the air in to the heat sink, over time this can clog up the computers heat sink reducing its effectiveness. Because of the dust your fan may have to blow faster making it louder and more costly to run. Normally you can see if the fan is clogged up simply by opening your computer up and looking at it. If your fans heat sink is really clogged up with dust and dirty looking it is a good idea to give it a clean. When dealing with the inside of your computer or anything electrical ensure the power is turned off and it is unplugged first.

The best way to clean out the insides of your computer is by using a can of compressed air and special nozzle, you can buy these from any good computer store. The spray nozzle is useful for getting in to those tricky places. When spraying the compressed air on to your computer, make sure you don't spray it for to long as condensation may form some drops of water. After blowing away any dust from your computers heat sinks give it a gentle wipe over with an anti-static cloth. You can also use the compressed air to clean the power unit and keyboard.

Cleaning the inside of your computer doesn't take long providing you have the correct equipment, and once done you notice an immediate improvement in your computers performance. The fan wont need to blow as hard so it will be quieter and thanks to the processor running at a cooler temperature your whole computer should generally run faster. I try to clean my computer every 4 or 5 months or so to keep it running efficiently.