an. Now, we are going to clean the inside grills of the power supply and get that dust back out. From inside the PC, clean the grills on the power supply until they are clean while stopping the fan from the outside.
Cleaning the Power Supply Grills

Many modern computers (especially gaming machines) also have another fan on their video card. If you do have a fan on your video card, stop the fan with something and spray it until its clean as you did with the other fans.
GPU Fan

Those are the most critical areas of your computer cleaned, you also may want to clean up any other parts of the computer that collect dust. In our example, the fan grill on the front of the case is also filled up with dust so I gave it a quick clean.
Cleaning the front Fan Grill

To finish up, I give the whole case a spray with the air which includes the motherboard, RAM, cables and the bottom of the case to blow away any dust it already had and dust that had fallen while we were cleaning the other parts.
Clean Computer Case

Finally, once your computer is clean, just close up the computer case in the reverse way you opened it.