Introduction

Most people think computers, being electronic devices, don't require any mechanical maintenance, but this is not so. Many computer faults are caused by components overheating due to poor airflow in the case because of a buildup of dirt and dust over time. It's worthwhile cleaning your computer annually or even more often if it is in a particularly dusty environment, on carpet or in a household with pets. This tutorial is designed to help you safely clean the interior of your tower or desktop PC so as to maximise its lifespan. No computer knowledge is assumed other than familiarity with component names. Cleaning the computer is not rocket-science and does not require any special skills or tools but you do need to know how to avoid possible damage to some of the more sensitive parts. That's what we will demonstrate here. Although the same principle applies to laptops and notebook PCs, because of the difficulty dismantling them these instructions do not apply to those types of computer.

Opening the Case
The standard tower case usually has either a single metal cover covering the top and both sides, held in place by three or four screws or has removable side panels each held in place by two screws.

Cleaning the Interior

1. Case vents and PSU vents Run the vacuum cleaner nozzle over any air vents at the front, side and rear of the case and over any vents in the PSU especially the air vents in the sides of the PSU inside the computer. If the covers have vents then vacuum those as well.
2. PSU fans Use the blunt, insulated end of the pencil to hold the fan blades steady and blow compressed air into the PSU fan(s) and through the PSU. Significant dust may be ejected from the power supply .
3. CPU fan and heatsink This is the most important part of the cooling system - dirt collects on the fan blades and clogs the heatsink vanes. Use the paintbrush to brush the dirt off each blade and off the heatsink vanes if accessible. Using the pencil to hold the fan blades still, blow out the fan and the heatsink with the compressed air. It is important not to let the CPU fan (or other fans) spin up under the air blast as damaging voltages can be generated through a dynamo effect. Expect significant dirt to be ejected from the CPU heatsink. If you want to be particularly thorough moisten a Cotton-tip with glass cleaning fluid and wipe down the upper and lower surface of each fan blade.
4. RAM Sticks and Expansion Slots Dirt can sometimes build up in 'drifts' around the memory sticks and the video, sound or modem card slots. Use the compressed air to blow it out. Do not use the brush here. Cleaning a RAM slot.
5. Case fans Cases often have one or more fans attached to the front or rear panels. Using the pencil to stop fan rotation blow the dirt from the case fans with the brush and compressed air.
6. Video card fan and heatsink This can be hard to see as it is usually on the lower side of the video card. Depending on the design either use the paintbrush to remove dirt from the heatsink and/or use compressed air while holding the fan still with the pencil. To do a thorough job will probably require removing the Video Card which is normally held in place with one screw where it meets the case. Remove the screw and unplug the card by pulling firmly outwards. There may be a plastic latch at the back of the card, press down on this to help eject it. If you do remove the video card keep good contact with the PC chassis as often as possible to minimise static buildup and rest the video card on part of the case while it is being cleaned. When the fan is clean use compressed air to blow out the video card slot, on older cards if the edge connectors of the card look tarnished clean them lightly with a pencil erasor. Reinsert the video card making sure the plastic latch clips into place indicating the card is properly seated in the slot (not all systems have a latch). Then do up the screw. Video Card Fan.
7. The case Vacuum the dust from the bottom of the case being careful to keep the nozzle away from the motherboard. Spray some paper towels with glass cleaner and wipe down the flat metal surfaces of the case and the inside of the cover(s). Chasing
   
8. The Ports Dust often accumulates in the I/O Ports where you plug in peripherals on the back of the computer. Use the brush and compressed air to clean them out. Cleaning the I/O Ports.
9. CMOS battery Although this is not a cleaning process, if your PC is more than a couple of years old this might be a good time to change the CMOS battery - usually a round, silver-coloured button battery e.g. Energiser CR2032 Lithium 3v. The battery 'pops' out of its holder with a little pressure on the side near the clip and the replacement slips in. Note: Changing the battery may reset some BIOS options to factory defaults so If you have complex BIOS settings because of SATA drives, USB keyboards, RAID controllers or network parameters for example it would be best to note down all the settings before changing the battery and check for changes afterward.

Reassembly
Make sure nothing has been left inside the case and nothing is likely to get caught in the fans. Any cables that were moved to get access to other items should be put back in place. Inspect the cables going to the optical drives, floppy drive and hard drive(s) to check none have been dislodged. Put the cover(s) back on the system and do up the screws to hold them in place. Unplug the power cable and return your PC to its normal location. Connect up all the cables that were originally present (following the colour code if ygu used it) and reconnect the power cable. Plug into the power outlet and switch on. Make sure your monitor is switched on and check the computer boots up normally. Now you can use the CD lens cleaner if required.
Conclusion
We hope this tutorial has shown you that, with a little knowledge and a few basic tools, cleaning the inside of your computer is a simple, hazard free process. Following the above steps should have enabled you to successfully clean your computer so that it can continue to run as efficiently as it was originally designed to do.