Helping people with computers... one answer at a time.

Airflow through your computer is an important part of keeping it cool and running well. Frequently fans are just blocked by dust and dirt.

For some reason, my computer randomly shuts down a lot. It's been happening even more and more. It started around the start of summer. It usually would shut down for no reason. Yesterday, it said Over Temperature. This shutting down thing is annoying. When I'm trying to do work, I lose it all and the computer shuts down. I asked my cousin, he said that it could be my fan. I haven't checked yet, I'm going to ask you first, is it my fan? Or is it another problem?


The "Over Temperature" is definitely a clue, and the fan is a definite possibility.

But ... let me tell you a little story about dust bunnies, first.

For those who might not be familiar with the term, "dust bunnies" are clumps of dust and debris that form in and around computers, furniture and other areas that might not be getting cleaned regularly.

Dust Bunnies

We might not think much of them, and indeed, in places where they exist it's typically because someone isn't thinking about them very often.

But here's the dirty (no pun intended) secret:

Dust bunnies can kill computers.

As you've noted, your computer has at least one, and possibly more, fans that move air through its case. The computer's components generate a lot of heat, and the purpose of the fans is to keep the computer cooler by pushing warm air out and pulling presumably cooler air in.

The problem is that the "pulling air in" part also attracts dust and dirt that might be floating around in the air as your computer is running. The dirt then accumulates into larger clumps that end up blocking the vents that air is supposed to move through.

And this can happen both inside, and outside your computer.

The result is that your fans might well be running, but because the airflow is blocked they can't do their job. In fact, the fans themselves end up adding even more heat to the mix which has nowhere to go.

As a result, your computer overheats and crashes.

As you might imagine, the solution is fairly clear: keep the area around your computer clean and clear.

More specifically:

  • Make sure that there is room around your computer, particularly around the vents in front and back, for air to flow.

  • Place your computer in a cooler part of your room, or near some natural air flow if you can.

  • Vacuum around your computer, particularly behind it, on a regular basis. How often will depend on just how quickly dust bunnies form in your particular location. If you're actually seeing clumps, then you've probably waited a little too long.

  • If you're already in the "covered with dust bunnies" stage, shut down and unplug your computer, open the case, and then with a brush attachment gently vacuum out the interior. Pay particular notice to the location of the fans, and any accumulations of dust and dirt.

  • While you have your computer open, and after you've cleaned it and put the vacuum away, plug it back in again for a few seconds and make sure those fans are running. If not, then perhaps they've been damaged by getting clogged with dirt and need to be replaced.

It's an easy thing to overlook, and I've personally seen some seriously over-looked computers in my day. Smile

The good news is that it's also an easy thing to stay on top of, and it's worth it. There are enough other things to go wrong, we don't need killer dust bunnies to add to our problems.

Article C3573 - November 24, 2008 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

November 25, 2008 8:10 AM

Case in point: I make it a habit to regularly dust the inside of my computer--once every maybe 3 to 6 months. This past Saturday, I did just this. And, through a temperature monitoring software I use, I noticed the temperature drop almost 15 degrees (F). You might not get this drastic of a difference, though. I actually take my video card out, take my heat sink off, re-add thermal gel to the processor. All in all, I think it's worth it though.

November 25, 2008 8:15 AM

I had this problem. It would have never occurred to me that it could be bad RAM, but I was lucky enough to find an article about it and, sure enough, after I replaced the memory all was fine. It was an inexpensive and instantaneous fix.

Danny Wilson
November 25, 2008 8:24 AM

"My computer has started to shut down randomly, could it be the fan?":

Another way of preventing dust build up is use your vacume cleaner nozzle ( Plastic ) I must add to clean and suck out all air holes in Pc Case also inside too this keeps most fans runing smoothly. From Danny

November 25, 2008 8:32 AM

About my comment above about bad RAM... in my case, I was not getting "over temperature" notification , so it is more likely dust buildup.

Connie Rhyno
November 25, 2008 8:37 AM

You know, we all to often take our computers for granted, they are like anything else, ... if you look after them, "they" will look after you!! Thanks for pointing out how important it is , to keep our computers"clean"!

November 25, 2008 9:16 AM

Did you know, the dust in your computer is like 85% dead skin. Think about it.... :)

It's always a joy for me to fix and clean other people's old, mothball filled systems. You would think they never knew how to use a vacuum. Compressed cans of air ftw!

November 25, 2008 10:10 AM

Two things: 1. The dust can cause a lot of noise, too, depending on how the fan is structured. 2. You forgot to mention that one doesn't have to "lose all" when the computer shuts down. Any old hand will tell you he saves what he is doing every few minutes, and sometimes every few seconds. I automatically do a CTRL-S after virtually every editing change, and every paragraph input. After "losing all" once, there's really no excuse for getting caught a second time. Whatever the program you're using, just think, "Would I want to have to type all this in again?" When you do that, you'll automatically do a "save" often.

Yes, I confess to being a CTRL+S addict as well. Been burned too many times. Even wrote an article on it: My computer froze, and I lost my work in progress - what can I do?
- Leo

November 25, 2008 11:53 AM

I've found that improper cleaning can cause more harm than good. Regarding using a vacuum to clean the interior of your PC, this can be dangerous since static electricity can be generated by the vacuum and cause damage to PC components. A bit more troublesome but safer way to clean the interior of a PC is with short bursts of compressed air making sure that the can is not shaken or that moisture is expelled from the can while cleaning.

Personally I've not had problems with careful use of a vacuum, particularly for the exterior. But you are very correct, care and caution are called for particularly when cleaning the inside.
- Leo

David Edwards
November 25, 2008 1:19 PM

But what if the whole dust bunnies thing does not apply and there are no messages? The fan(s) seem OK and temperature does not seem to be the issue due to the randomness of the problem. Could it be software related?

Of course ... it could be software, and it could also be other hardware related reasons. Random shutdowns can happen for many, many reasons. In this article's case the overheating warning was a clue that helped direct the investigation. For other causes, hopefully there'll be additional information besides "it just shuts down".
- Leo

Shawn Patrick
November 25, 2008 1:27 PM

Leo.. I'm glad that you presented this article on "Dust Bunnies" There are many out there that will benefit from the info. Any time I do a major clean up of my PC I open the power supply and clean it. I uncouple all my connections inside my PC and reconnect them back. (this creates a good connection)(do one connection then reconnect, then go on to the next connection, this way there are no errors).. I clean out the heat-sink using a small brush and a piece of cardboard. I remove my audio and video cards and wipe off the contacts on them with a soft lint free cloth and brush out the slot where they came from. Remove the memory sticks (RAM) and wipe of the contacts with a soft cloth. It is also essential to buy a couple of cans of compressed air to blow out the dust from the inside of the PC.. Ensure that the components on the motherboard are free of dust as well. Note.. BE very careful of static electricity that may come off you when handling any of these components... it could damage what you are handling. I perform these tasks at a slow and thoughtful pace. I'd suggest that you do a (Google search) on How to clean the inside of a computer. Thank you Leo for all the articles I receive from you each week and the comments from your readers.

November 25, 2008 2:00 PM

An often forgotten aspec of computing; keeping it cool. I saw a reference in the replies to use compressed air. I would like to add to this "with caution" as a full can can often dispense the air with in it in it's liquid form and damage components. I rebuild old computers to give away to school kids and one of my most used tools is a small cylindrical two-handed pump used to blow up those long balloons that make animal shapes, it cost about $4 from a toy shop and with it's pointed nozzle I can get right into the processors vents without removing the heat sink.
Another tip for users: IF you have to place your CPU on the floor, put it on a small box. Just getting it 6" off the floor makes a lot of difference as to how much dust is sucked in.

November 25, 2008 3:33 PM

Pay particular attention to the heatsink blades mounted on top of the CPU and on top of which the system fan is mounted. Dust often gets clogged between the blades and is difficult to see from the outside. I usually need to carefully remove the fan to clean it with a thin blade. If you otherwise clean your PC but still get overheating errors then this might be your problem.

John Thompson
November 27, 2008 2:23 AM

Occasionally the cause can be hardware. About 15 years ago I had a similar problem; I don't remember if the Pc shut down or complained of a memory error. The PC supplier eventually found a pin bent over when he removed the CPU!

November 27, 2008 4:51 AM

Additional reason for shutdown may be a problem with the energy supply which comes in a "block" with several plugs (wires) to connect to hard drive, cd/dvd drive etc. If that one is failing, pc will shut down on regularly and unexpected (no warning) moments and sometimes not start at all, even after hitting the power button on-off, sometimes until you wait for e.g. 30 minutes or 1 hour.

So yes, first possible cause of the shutdown is that the fans do not properly work, whatever the reason may be (dust, not powerful enough, bad power contact etc.). The second one is the energy supplier itself.

Also software failure is a possible cause, though hardware not functioning, the most probable.

larry L
November 29, 2008 4:04 AM

I have a dedicated computer for security with several cameras. I have had many many warnings of system overheat. Over the weekend sometimes I found the computer shut down on monday and had to reboot it. There were no dust bunnies and I cut a hole in the side of the case and installed a 6 inch 220 volt fan. The problem continued for about a year then it started failing every hour. The FIX was to replace the 1.2 year old power supply. Craziest thing I ever saw. But its been working now for 4 years without a hitch.

Kenneth Crook
November 29, 2008 6:26 PM

Vacuming can be dangerous.
While cleaning the keyboard of my notebook I was using the brush attachment on the vacum cleaner hose to clean the keyboard. This worked good. So I thought using the hose attachment without the brush would work even better. It sucked three keys off the keyboard. Luckily I had just replaced the dust bag so I found all the parts to the keys. But it was a real hassle getting the keys back together.
Fred Langa, on one of his newsletters had a really good article on cleaning computers, with tips and dangers to watch out for.

November 29, 2008 8:03 PM

I've also seen the blades of a cooling fan physically blocked by a wire inside the case. With more and more elements crammed inside, many of which have multiple wires running to and from them, it's very important to close the case carefully and then make sure the fans are operating properly. A high-frequency clicking sound can also be a warning that a wire is starting to brush against a rotating blade. Not only can this cause over-heating, but there is a real possibility of an eventual short circuit if the insulation is completely worn off the offending wire.

David Irwin
December 1, 2008 12:46 PM

Another possible cause is the motherboard itself. There is a temperature sensor on the board under the processor. If that sensor has failed and is indicating an extremely high temp, the board will shutdown. This is usually a surface mounted, non-replaceable component. The fix would be a new motherboard.

Brandon Wood
December 1, 2008 2:05 PM

To clean the inside of my computer, I simply use a drinking straw with the bottom taped (with electricians tape) inside of the edge attachment on my vacuum cleaner.

Just wrap the tape gently around the straw until all the suction is coming from within the straw only. When finished, just peel the tape off along with the straw and throw it away.

This makes getting into the fan crevices so much easier and insures that I don't accidentally ram my hardware components with the hard vacuum attachments.

Of course there are are micro attachments that you can also buy, but this method is cheap and works well enough for me.

Martin Kaplan
December 2, 2008 2:12 PM

re: oveheating and cleaning...would it be wise to install a fan running at low speed a few feet away from the unit?

Yes and no. Yes, in the sense that it's likely to help, but no in the sense that it shouldn't be needed except if the computer happens to be in a particularly warm environment. Normally a well ventilated and clean machine should not need dedicated additional external cooling.
- Leo

Ed Vance
December 6, 2008 2:44 PM

Just one thought from me.

SAVE your work about every 15 minutes to the Hard Drive so if something goes wrong all you have lost is 15 minutes of your work.

St. Pete Tech
February 25, 2010 11:25 AM

Besides the fan being free of debris and working properly, another culprit to check is the Thermal grease between the processor and heat sink. It is a gray gel-type liquid deisgned to help "pull" heat away from the processor. Remove the heat sink and clean the bottom of the heat sink and top of the processor gently with a small amount of rubbing alcohol on a rag or paper towel, then apply a small bit of thermal grease and reseat the heatsink. Obviously, remove the power and battery brfore you do this, there is no need to remove the processor if you are careful...

Gaurav Vashishtha
April 18, 2011 6:25 AM

Hey guys! M also facing similar kind of problem with my PC. My PC gets off automatically at any time..I called a computer expert and he suggested me to replace SMPS(power supply switch) but it didn't helped me..Some times my PC work well and works for hours n some time it gets off(not shut down, it gets off) frequently...what could be the probable reason for that?

Jonathan Fernandes
October 8, 2011 3:53 PM

Does were you place you computer contribute to this. When i put my computer to convert a movie for me, it shuts down after a while in to the conversion. This happens when i place my laptop on a 'wooden' surface. But this doesn't occur when i place it on a glass surface.

I could if something blocks airflow or prevents the computer from cooling as it should.

October 8, 2011 6:34 PM

That seems very likely as the glass surface would be a lot cooler.

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