In the following steps you will be using isopropanol, also called cleaning alcohol, to clean your computer.
Work in a well ventilated space. isopropanol is volatile and fumes off quickly. It is not healthy to breath isopropanol fumes. Set up a fan to blow away the fumes from your work place.
Here you can see a Noctua fan, an excellent choice. It is the highest quality fan on the market for electronic cooling applications, and it is inaudible in operation.