Is your computer running slowly? The culprit could be dust.
The vast majority of computers are cooled by air, and most of the time this is done with fans moving room temperature air past the much hotter internals of a computer. Metal heatsinks sit on the hottest parts and draw the heat away from them. The air being moved by the fans cools off these heatsinks and carries the heat out of the computer's case.
If dust collects inside a computer, it can clog up fans, heatsinks, and other parts. This reduces the airflow and thus the effectiveness of the air cooling system. Your computer has temperature sensors in key places to sense when parts are getting too hot. In order to keep these parts from burning out, your computer will automatically decrease performance so they're generating less heat to begin with. In extreme cases, the computer will even shut off to save its self. In the photo here you can see two heatsinks caked in dust. Air is unable to get inbetween the fins of the heatsink, so the center of them remain hot. It's even possible for dust to encase a fan so much that it stops spinning.
Everyone has dust in their computers, even those with the cleanest homes. These airflow cooling systems do one thing all day: pull air through the computer's case. It's inevitable that dust is going to collect in the system.
I recommend that every so often - once a year is probably enough - you take your computer outside and use a can of compressed air to blow the dust out of the system. You may need two cans, since they can lose effectiveness the more you use it (and they get really cold). Laptops are just as susceptible to this problem, so make sure you clean those out too.
This is a project you can do yourself, but you might be wary of the delicate components inside a typical computer. If so, give us a call and we'll give that computer a thorough dusting!
Fun fact: in the beginning of this post I mentioned that the "vast majority" of computers are cooled by air. Another cooling method (generally only used by hardcore PC builders) might surprise you: water! Water cooling can eliminate the fans in a case entirely. Water is pumped through tubes the pass over blocks placed on the important heat-generating components, and is then usually brought out of the computer where it's fed through a pump that cools the water down before it's fed back into the computer. It's a very effective cooling method, but it's pretty expensive and clearly the effects are pretty bad if there's a leak anywhere in the system.
Tip: this post was just as much about air cooling as it was about dust. Air cooling uses ambient air to cool down a computer, but that air needs to be relatively cool (room temperature) to do its job. You can have a squeaky clean computer but if it's being cooled with warm/hot air, you'll see the same problems I described above. For this reason, I urge my clients to make sure there's a decent amount of room around their computers so the air has somewhere to go. One of the worst offenders of overheating are the "computer desks" (like the one pictured here) which include a compartment where you can put your computer and close a door in front of it. This creates a compartment of hot air that doesn't recycle. Keep your computer out for the best performance and the longest life.