this outside to prevent the dust form going all over the room. First shut it down and unplug it from any power source.

Open the case by using a Phillips head screwdriver to unscrew the screws on the back of the computer and slide the panel towards the back of the computer. Typically, if you are looking at the front of the computer, you will want to open the left panel because this provides the best access. Some brand name computers such as Dell, Compaq or HP may have hidden screws and clips elsewhere which will need to be found and released before you can open the computer.
Opening the Computer Case

To begin, we will clean the CPU fan. If you are using a compressor, first give it a test spray of air because sometimes they can collect moisture and spray water onto your computer which is something we definitely don’t want. After, place the pen or pencil in between the fans blades to prevent it from spinning and blast the dust away from the fans blades.
Cleaning the CPU Fan

Next, you will need to get the dust out from the computers CPU heatsink just below the CPU fan. A good blast from a low angle facing towards the back of the case should get most of the dust out from in between the aluminum grills.

Now we will focus on the power supply. Place the pen or pencil into the fan on the back of the computer (up near the top of the machine for most computers) and give it a good blast from outside of the computer, into the fan as shown in the photo below.
Cleaning the Power Supply Fan

Although the above step pushes dust into the power supply, it is the most effective way to clean the rear f