Your PC can get dirty inside and out. Here's how to blow the dust out of a PC and clean a clogged port.
Clean a Dusty PC
If you allow your desktop PC's case to get dirty over time, grime can clog the fans that keep the internal parts cool. If airflow is blocked, those parts could overheat.
First, shut everything down, and unplug all the cables besides the power cord. Touch a metal part of the case (such as the PCI-slot cover) and then unplug the power cable; doing so will discharge any potential static externally, instead of damaging electrically sensitive components inside. Wear shoes, and work in an uncarpeted room.
A few more precautions can add further protection. Use a layer of rubber (such as mouse pads) between the PC and your worktable. Wear an antistatic bracelet, and connect it to a metal part of the PC chassis.
Open the PC case. Many cases have side doors held in place by a single Phillips-head screw or thumbscrew; consult your system's manual for specific directions.
Pull out any loose clots of hair, dirt, or other obstructions. Then use a can of compressed air to blast anything else away and out of the PC. Keep the can upright, and press the trigger in a series of short bursts. Use the nozzle straw to direct the flow close to your target.
Blow grime up and out of the case if possible, but focus your attention on clearing clogs at vented areas. Blast through grating, and blow from inside the PC, out through the power supply's fan, until you no longer see any dirt being cleared away.
While you're inside, make sure that the internal cables are clear of the vents. Use cable ties to fix them to the sides. Reclose the case, and reconnect everything.
To slow future dirt accumulation, try to keep your PC off the floor, since that's where much of the grime originates. Repeat this cleaning process annually, especially if you have pets.
Clean a Clogged Port
Over time, ports on your electronic equipment can become clogged with dust and other debris. If you're having trouble getting USB or other devices to work with your computer, cleaning any grime from the connecting ports is a good first step.
Turn off the hardware first. If you can see that the port is severely clogged--say, with peanut butter or another thick, child-friendly substance--gently dig the gunk out with toothpicks. But remember: Ethernet, serial, and other jacks rely on fragile pins, so try to move in and out on the same path instead of swirling around the sides.
For less sticky situations, use a can of compressed air (actually pressurized gases) to blast out loose bits. The cans sell for $5 to $10 at any computer store. (Keep them away from children: The gases are dangerous to inhale, and they come out extremely cold.) Fire at the target in short bursts.
Finish cleaning with a cotton swab dipped in rubbing alcohol or electronics cleaner. Leave the device turned off for a couple hours to dry.