Enemy #1
The number one enemy of computers is heat. Excess heat can damage components outright, or cause accelerated wear over time. Especially with laptops and all in one machines, a great deal of engineering goes into conducting heat away from the computer components and moving it outside of the case.
So your job is to let the computer’s cooling system do its job. Make sure that the ventilation holes and grilles of the machine are clean and free from obstruction, make sure that the fans are operating properly. Use a computer on a hard surface, never use a computer on a soft surface or on fabric (like blankets or a soft carpet) because the fabric will both block the cooling vents and hold the heat in by insulating the machine.
My pad or your pad?
A solution for laptops that get excessively hot is a laptop cooling pad, which provides a hard surface (often with an ergonomically advantageous angle) and either passive or active airflow around the laptop’s case. Active models have from one to three fans, which typically run off USB power and move air past the bottom of the computer to carry away heat.
Dust bunnies, unite!
Dust loves computers, it will collect wherever there is airflow and static electricity. The grilles and vent holes of a computer case, and CPU coolers, fans and fan housings are prime areas where dust will cause problems.
You can clean out a computer with compressed air with bottles of ‘canned air’. We prefer a more ecologically-sound method which is a specialized blowing unit that runs on AC power (like a reverse vacuum) and does not vent any chemicals or create metal waste. Be careful with the air flow, and don’t send it directly into optical drives or floppy drives, where the air pressure could damage the delicate heads of the drive.
We do not usually recommend using a household vacuum cleaner on a computer – airflow through the vinyl hoses of vacuums generate a lot of static electricity and in a worst case scenario may damage computer components. However, if there is no other option for cleaning a machine, you can suck out the dust carefully.
However, just blowing out a machine from the outside may not be sufficient – the best way to clean a machine is to open the case to get access to the components. This is easy enough with a PC tower, but for notebook machines and all in ones like the iMac, disassembly is more complex and it may be better left to an experienced tech. Here is the example.
We took pictures of the insides of an iMac before cleaning, and then reassembled it and blew air through the grilles as thoroughly as we could from the outside. Then we took it apart to see the results (click on the image for the large version):
Not too impressive, right? There’s no substitute for opening the machine to clean it properly.
Hint, if you have to disassemble an iMac, recent models require the screen to be lifted out. Go to an auto parts store, and invest in a pair of the large suction cups that are sold for pulling out dents. This is a much more secure way to lift the screen. Whatever you do, don’t use metal tools to pry around the edge of the glass.