On Computers

Cleaning Your Computer Case

Gail Allinson, gail@oncomputers.info

22 June 2003

A few weeks ago Jack covered a subject unto itself: cleaning your keyboard. This week I'm talking about cleaning that big box that usually sits on the floor or the desk.  It is the part that many call the CPU, but is more properly called the System Unit.  Sometimes I just call it the "dirt magnet".  Not only do most computer cases have at least one fan sucking air into the case, but they also have nooks, crannies and even electricity which may cause the dust, dirt, and general crud of your life to collect within its six sides.


The first and easiest part about cleaning your computer case is keeping it clean. This means that you should keep the environment around the computer clean.  Some ways to do this are to keep your dwelling's furnace and air conditioner filters clean. You might even use  an air cleaner in the room where you keep your computer. Don't eat or drink around your computer (yeah, right -- I don't follow that one) and if you smoke try to keep it away from the computer.

I have found over the years that regularly vacuuming the floor around and under the computer is a big help.  I also try to keep the dogs and cats from sleeping right next to the fans or air vents on the case. Fur is one of the things that can and will get into your computer if you have pets. I also use filters over the case fans which blow air into the computer.  If you are trying to figure out which fans do what, it is usually the front fans or the lower fans in the case blow air into the case, while normally the back fans or higher fans suck the air out.  There are also usually one or more fans in the power supply.  If you don't know where your power supply is, just look for a metal box that the power cord plugs into. I do not put filters on the power supply. 

What I do to filter my fans is to slip a piece of air conditioner filter material between the plastic front bezel and the metal of the case to cover the front fans.  Air conditioner material costs about $2 a package and can be found at your local hardware store. Air conditioner filters are thin sheets of foam made to let air pass through it. Not just any thin foam will work -- some is closed cell and will not let air pass.  Some people rig up filters out of old nylon stockings. While they are a good filter material, I have yet to find a good way to keep them in place.

You can also buy special fan filters.  I think one of the best selections of fan filters is found at http://www.directron.com/filterguards.html. They come in styles and sizes to fit just about anyone's fans.  The aluminum filters are very nice, but they can get pretty expensive especially if you are filtering more than one fan.  However, if your fan is in a place where it shows, one of the prettier filters may be well worth the extra money you spend.

I clean my filter(s) about once a week, but there is no set schedule.  In a dusty environment once a week is not enough and in a clean environment, once or twice a year may be all you need.  If you do use a filter, just remember that you will have to keep it clean or it will get clogged and block airflow into your computer case.  In the case of air conditioner material, it can be washed in mild detergent and water, or merely vacuumed.  I usually just vacuum mine.  If you wash your filter, be sure to thoroughly dry it before putting it back in the case. You may want to cut two pieces of filter so you have "one to wear" and a spare.


After prevention, the next thing is cleaning the exterior of the case. I think it is a good idea to turn off and even unplug the computer even for cleaning the outside.  First, vacuum it thoroughly. I use a little dusting brush attachment. These come with most vacuum cleaners.  If it is not clean, thoroughly wash and dry the dusting brush before using it on your computer. After the case is thoroughly vacuumed, you can use a damp cloth or sponge to wipe the outside.  Light dirt usually comes off with plain water. If it is too dirty and plain water doesn't work, try some dilute, mild detergent in water. Whatever you do, wring out the sponge or cloth -- you do not want dripping water around your computer. If desired, dry the case exterior with a clean dishtowel or you can just let it air dry.


(Note: anytime you work inside your computer care and caution is required.  You use any of the methods mentioned for cleaning inside your computer case at your own risk.)

As always, the first step is to properly shut down, turn off the power supply switch (if yours has a switch),  and unplug your computer from the outlet before working inside of it. You may want to move the computer to a different location for this next step, because you don't want the dirt you are removing to go right back inside your case.  If you don't know where the cables plug into the back of your computer, take notes, make labels, or make drawings before removing them so you can plug them back into the right places.  Many newer computers and peripherals have color coded plugs -- this helps a bit.

Next, you will need to open the case. I've always said that you can tell a geek just by looking at their computer case! It has no screws or it has thumbscrews or some other easy to open latch.  If you have never opened your computer the instruction manuals or manufacturer's Web site will have usually  have information about opening the case.  If your computer is under warranty and has a sticker to prevent you from opening the case, please understand that you may end up voiding your warranty if you go in, so you may decide to leave the dirt in there for a while.  Most computers these days are not so encumbered.

In general, there are 3 main ways to clean the inside: sucking, blowing and wiping. The first is sucking or using a vacuum to pull the dirt out. Sucking the dirt may be done with just about any vacuum.  I usually use the crevice tool for this maneuver.  The trick is to not actually touch anything inside the computer with the hose, nozzle, or tool you are using.  I have heard of some people modifying the vacuum hose and putting a straw or other small tube on the end to help get into the corners.  Still, the important thing to remember is to work carefully and don't touch anything.

The second method is blowing the dirt out. Blowing the air out is a similar to vacuuming.  You need to work carefully and not touch anything.  People use many things to blow the dust out, including the canned "air" dusters available at many office and computer supply stores.  If you use canned air, make sure you keep the can upright or you may damage your computer.  You can also carefully use an air compressor, or as I did this week, the blower end of a shop vac.  I think the canned air and the shop vac are a little easier for most folks to manage safely.  Whatever you do, you do not want to blast dirt into your delicate computer components.  Canned air made for the purpose will be clean.  The air from the blower of the vacuum or the air compressor may or may not be clean.  I solved the vacuum problem by thoroughly washing the vacuum and hose, putting in a clean air filter, and putting one layer of nylon stocking over the end of the hose to catch anything I may have missed.  This did an excellent job for me.  Some folks use their vacuum to suck in one hand while dusting with canned air in the other hand.  This method probably works very well and really takes the dust out of the area, but my objection is the expense of the canned air.  Same too with the expensive electronics mini vacuums and blowers sold at many office stores.

The third method is wiping.  Now wiping is even trickier in some ways than blowing or sucking.  I make sure I use something clean, dry, soft, cotton and lint free.  I only use the wipe method on the metal parts of my case -- particularly in the bottom of the case and I make sure not to touch any of the delicate electronics. I'm not sure why <g>, but I get fingerprints in the bottom of my case and the only way I can get them off is to wipe.

When you are done cleaning the interior, make sure to discharge static by touching metal (you don't want to touch and risk static damage to the electronic components) and gently press on cables and cards to make sure that they are  plugged in firmly before closing up.


There are other strategies to use to clean your computer case.  Just remember to protect delicate components from physical and static electricity damage.  For me the risk of not cleaning is worse than the risk of cleaning.  Not cleaning can lead to heat build up that may damage electronic components.

Before I close, I want to thank the members of the On Computers newsgroup who answered my question this week about using an air compressor to blow out the case.  Remember if you have questions, you too are invited to news://news.oncomputers.info/news.oncomputers with your questions. I still haven't used an air compressor inside the case because for me it is the most "dangerous" of the options as I can see my graphics card sailing trough the air if I try this.  Many people safely use air compressors, but I'm not one of them and I had a great alternative in my shop vac.

Here are a few articles about cleaning your computer:





Link to air duster pump that Deepak mentioned on air:


Jack's Two Cents Worth on Case Cleaning

Jack 'daWabbit' Imsdahl jack@oncomputers.info

 Don't let all our cautions about possible damage put you off of doing this essential maintenance on your computer. Taking care in the manner(s) specified will prevent any damage and you can do this. Should you choose not to do it, eventually you will have to take the box to a shop, where they'll do pretty much what we detail here and charge a fairly hefty fee for it.

There's no worse feeling than coming home to a computer beeping madly because the CPU has gotten too warm. This has happened to me, several times, and though I've so far escaped damage (judging by the fact that all the boxes are still running) it tends to happen at the worst time. Prevention is definitely the way to go, in this respect.

Compressed air from cans is cool, but not really affordable. Even with careful shopping, the expense adds up in a hurry. And you'll still have to do an awful lot of wiping, etc. to get things clean. There's enough pressure in those cans, but nowhere near enough volume to do a good job. They're handy to have around, but not a serviceable option for the long haul.

Air from a compressor is better. There are a number of hazards inherent in that, though. First and foremost is the temptation to use too much pressure. The parts of your computer are fragile and many of them are exposed, so you must be very careful. Limit air pressures to under 30 pounds per square inch with large nozzles and 20 (or even less) with small ones. Even if you use compressed air, you'll still have to do quite a bit of wiping or vacuuming to get everything cleaned up.

Many compressors put small amounts of oil into the product. Worn or "ringless" compressors are bad about this. Even in minute amounts, it can damage the components of your computer, so this must be avoided at all costs. Water condenses out of air as it is compressed and collects in the vessel. Use a water trap to keep this out of the stream.

I think the best solution might be the hand-powered pump Deepak mentioned that is for sale at CompUSA (and possibly other places). I'll be checking these out at first opportunity and will let you know about them.

When using compressed air; do not spin fans with it. Hold them still while you blow them off. Spinning them too fast with the air stream can damage them. Admittedly, this is rare. But it's not unknown and the damage would be cumulative and so worth taking pains to avoid. Care here can keep you from a 3:00 a.m. hunt for a replacement, too.

Most of my cleaning is done with cotton swabs and paper towels, though one has to be a bit careful these don't leave fibers or lint behind. There are foam-tipped swabs available, too, though I have not seen them at retail. The ones I have came from a doctor's office. These are reusable and leave no lint behind, if carefully used.

I do like the vacuum cleaner, too. It's a good way to start and finish by picking up all the loose stuff. I have occasionally heard that the hose of a vacuum cleaner is a hotbed of static electricity during operation, owing to the rush of air through it. I am not sure this is true, mostly because I have never found anyone who is not a self-appointed 'expert' to confirm it. In any event, any time you are working inside the case, normal precautions against static buildup and/or discharge should be followed and these almost certainly will be sufficient to protect things.


© 2003 Gail Allinson and Jack Imsdahl

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