Overheating: Enemy Number One

Category: Hardware

A reader asks: 'My computer sometimes shuts down at random times. A friend said it's probably overheating. How can I find out for sure, and what can be done about overheating?' Read on to learn why heat is your computer's worst enemy, and how to keep your PC or Mac from being damaged by overheating...

Signs of Overheating - And What To Do

Electronic components in your computer and other devices generate heat. The harder they work, the more heat they generate. But heat is the mortal enemy of all things electronic. So it's important to be alert to temperature spikes in your computer, and take steps to cool it down when necessary.

How can you tell if your computer is overheating, and what can you do to keep it from frying like an egg? Sudden, inexplicable shutdowns of your computer are often due to overheating. Other symptoms of overheating include declining performance after running processor-intensive tasks for several minutes or hours. Games may run sluggishly, video may skip, and response to mouse clicks may be delayed. More alarming are sudden software crashes, random reboots, and the dreaded Blue Screen of Death. These symptoms may have multiple causes, but overheating is one suspect that needs to be confirmed or eliminated.

heatsink fan overheating

The computer's BIOS (Basic Input/Output System) detects when the CPU, motherboard, hard drive, or graphics adapter is approaching its maximum operating temperature and shuts things down to avoid damaging that vital and expensive part. If you are experiencing shutdowns, measure your computer's temperatures and do something to lower them immediately.

Temperature sensors are built into many computer components; the trick is accessing these sensors to read temperatures. Microsoft Windows and Mac OS do not have built-in utilities to let users read temperatures. You have to find third-party software. Fortunately, there are several free temperature-monitoring utilities. Some can not only monitor temperatures but also do something to lower them.

SpeedFAN is a long-standing favorite temperature monitoring utility. It also monitors voltages in various devices and the speed of the fan(s) which cool your CPU, power supply, and other components. Some motherboards allow users to control fan speeds while others do not; if fan speed can be controlled, SpeedFan will do it automatically to optimize the fan's cooling.

NOTE: Unfortunately, there are sometimes misleading ads on the SpeedFan website with big "DOWNLOAD" graphics. Be sure to click the Download link near the top of the page (next to Screenshots). On the next page, look for "The latest version is..." You'll find the download link there.

Open Hardware Monitor is a free system monitoring program for Windows and Linux computers. It monitors all of the voltage, temperature, fan speeds and other sensors built into your motherboard, including CPU temperature.

Temperature Monitor 4.6 is a similar utility for Mac computers. It's part of a suite of Mac monitoring utilities written by Marcel Bresink, and it's available free of charge. This one does not control fan speeds.

CoreTemp is designed for Intel and AMD multi-core CPUs. It can monitor the temperature in each core in each processor in your system. It also has a logging feature to record temperatures over variable periods of time.

If you can find a fan-speed controller that works with your system, it will provide several benefits. First, it will keep the temperature of your CPU and other components under the critical level, protecting your hardware and preventing shutdowns. Second, it will extend the life of your fan by running it only when it's really needed. Third, it will minimize that irritating noise than cooling fans often make.

Other Overheating Solutions

A good rule of thumb is to make sure your CPU temperature is under 70 degrees Celsius, but each processor has a different safe operating range. I recommend that you see my article What's Going On Inside My PC? to find out what hardware is under the hood, and then search for information on the maximum safe temperatures.

If adjusting the fan speed doesn't bring the problem under control, there are several other possible causes for overheating. Dust is a common cause of overheating. You can buy cans of compressed air to clean the dust out of heat sinks, fans and airflow vents. Crack open the system unit every few months and you'll be surprised at how much dust accumulates there, and how it affects your system temps.

Adequate air flow is important. A tower system should be placed so that its vents are not blocked by desk, wall, or other obstructions. A laptop can be elevated on a lap pad to allow air to circulate under the machine.

It's possible that the fans themselves may need to be replaced. If a fan is noisy, that's a sign that it's not working properly. Some components have built-in fans that can fail. This recently happened to the graphics adapter on my desktop machine. My computer was shutting down unexpectedly, and SpeedFan revealed that the temperature of that component was hitting 120 Celsius (about 250 degrees Fahrenheit). After opening the system unit case, I saw that the fan attached to the graphics card wasn't spinning. As a temporary workaround, I'm leaving the case open and cooling things down with a small electric fan that clips on the side of my desk. Not pretty, but it works.

It could also be that the thermal seal between the CPU and the heat sink (which draws heat away) is not good. You can remove the heat sink and reapply thermal grease, but that's beyond the scope of this article. You can find YouTube tutorials on how to do that.

Do you have questions or tips on how to resolve computer overheating problems? Post a comment or question below...

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Most recent comments on "Overheating: Enemy Number One"

(See all 28 comments for this article.)

Posted by:

T. Natkin
13 Aug 2013

Dear Bob,
I'm freaking out!
I installed the latest SpeedFan, opened it and got (for the first ever with my 3-year-old PC with Vista)...a BLUE SCREEN!
Naturally, I went to Control Panel to delete it --and received the dialog box about removing something called GIVEO (I did), but the computer doesn't work as well as usual.
When I went to "System Restore," it was unable to restore the system due to "an error"!
I'm under pressure to finish a book edit and need feedback WHAT TO DO, desperately!!

Thank you!

Posted by:

13 Aug 2013

Dust always finds a way to my H-P Pavilion Elite m9040n. There's 1 vent on the left side of the case, 2 on the right side, plus 2 fan exhausts on the rear. All get their fair share of dust. I gently brush vacuum all portals and the front of the pavilion whenever I see an accumulation forming. Every other month, I disconnect everything and take the unit to the garage and remove the side panels. I disable the fans with plastic rods, which prevents damage via overspin of the fan blades. Since I have an air compressor, I blow a very low pressure stream of air to all surfaces. It's amazing how many "dust bunnies" get removed! I can't emphasize enough how important it is to: 1. Disable the fans; 2. Use low pressure; 3. Don't touch any components with the air nozzle. In fact, I'm super selective when it comes to sharing this info. (There are people out there who should not even be operating light switches)

Posted by:

Mervyn Doobov
13 Aug 2013

In my experience, cleaning out the computer to remove dust does wonders in this regard.

Purists won't like it but I usually use the vacuum cleaner in reverse (blow instead of suck) and a can of compressed air for harder-to-reach spots.

By similarly cleaning all the fans, there is also a great reduction in noise.

Posted by:

13 Aug 2013

Hello - I just clicked the link for SpeedFan. That page tells me lots of info about their creation, but NO INFO about installing it or using it. Do you have to be a computer techie person to use it? Am I missing something obvious? What link would you suggest for us novices that need a user-friendly utility for their PC?

EDITOR'S NOTE: Click the Download link near the top of the page (next to Screenshots). On the next page, look for "The latest version is..." You'll find the download link there. Just beware, there might be some misleading "DOWNLOAD" ads on the site. Avoid those.

Posted by:

14 Aug 2013

great work bob.

Posted by:

14 Aug 2013

Sometimes the BIOS will have fan settings and adjustable max temperature settings.

Posted by:

14 Aug 2013

The points that you make are all very good. My system has variable speed fans and when the system really gets working hard you can hear the fans speed up. When they don't slow down quickly after the extra intense work is done I know that it is time to crack open the case and clean the dust off of the components. My big problem has been trying to get the dust out of the fins on the CPU heat sink. Although there is a clamp holding the heat sink in place that is fairly easy to release that is not the only thing holding it in place. It appears to be held by screws as well. In the past I had used a 3/4" paint brush to attempt to remove the dust. It could not reach all of the deepest places in between the fins. I have never tried canned air as I have found that blowing dust around is not completely effective. From my experience with blowing dust in a wood shop I have found that there is always a thin film of dust that blowing will not remove.
Last time I cleaned the dust from inside my computer case I used a vacuum to remove most of the dust in the case, but there is still a thin film of dust on the components. I used the paint brush to stir that up so it could be vacuumed away. But the dust still remained on the heat sink fins. I found brush that looks like a very small bottle brush, the bristles forming a column that is less than 1/4" in diameter. I slid that between each of the fins while holding the vacuum nozzle nearby. Since doing that at the start of the summer I have not had any incidents of run away fans.

Posted by:

14 Aug 2013

Piriform de-fraggler, a free program that among other things constanly measures the health and temperature of your PC.

EDITOR'S NOTE: Defraggler measures only your hard drive temps.

Posted by:

14 Aug 2013

I have used core temp with rainmeter's app for it, and have it notify me when it's getting close to dangerous. Having the task manager handy is good too, for if I'm running my digital comic app and a video conversion program it starts to overheat my comp. I can usually pause my conversion, grab my laptop cooling pad, and can resume. But can close the comic app if things get out of control otherwise.

Posted by:

14 Aug 2013


i THINK WHAT YOU MEAN ARE 'INTRA-DENTAL ORAL CARE BRUSHES'. They are about the thickness of a pipe-cleaner only about a half --or a bit less -- in Diameter. And can be bought at nearly any drug store. Often they are better than other 'brushes' because many brands have a NYLON CARRIER - which means the brushes are attached by Nylon rather than placed in twisted metal (a very good conductor: To paraphrase Shiva, through a paraphrase of Oppenheimer: "I am Become Death" to your computer). There are many shapes, I find that the conical (as opposed to the 'cylinder' shaped) are the most useful shape, though I really wonder how much good such work would accomplish in a time-cost-benefit/life expectancy of your computer analysis.

I use canned "air' cleaners out in the desert and a low pressure nozzle on an air compressor to blow out my computer when I give it the 'complete' cleaning twice a year (spring and just before winter, call it mid-Autumn) and about a 10-15 minute (start to stop) 'blowout' every couple of months. You hold the fans in place with wooden dowels to clean them off so they don't spin on you, though I find an anti-static cloth FAR more effective than air but there are many ways to skin a cat.

I REALLY hope that someone out there has a solution other than throwing more air at a board (CPU-GPU-RAM). Many of us use our Lap-Tops as tools that don't sit on pillows, but either in our lap, on a flat 'desk' surface, or on the seat next to us in our FWD. Often it's easier to enter numbers 5 or 10 at a time, than it is to do the mind-numbing entries at the end of the day.

I mean, really, The ONLY solution is to throw more air at something to cool it?, nothing made to filter or cool the air at all?

Posted by:

14 Aug 2013

Great topic!

A friend's Dell desktop shut down shortly after starting. We discovered the plastic bracket holding the heat sink to the CPU had broken and wasn't in contact anymore. New brackets were very available online, varying in cost from over $10 to $1.23 (shipping included from China). Repaired the broken one with fine safety wire. Works fine now.

Same problem with a laptop, and cleaning the cooling air inlet solved that one.

Mayonnaise works as thermal paste if you don't have any "real" stuff. http://www.hardwaresecrets.com/article/Thermal-Compound-Roundup-February-2012/1490/5

Posted by:

15 Aug 2013

The only thing CoreTemp did for my Lenovo Vista desktop was lock it up and required a re-boot. Have dual Intel CPUs but the MB may have had issues. Not sure the BIOS/MB has temp sensor capability anyway so maybe that's why. The P/S fan does a roar at boot (and sometimes is accompanied by a small cloud of dust...) then settles down so I know it is a variable speed fan. Haven't looked inside so don't know if there are any other fans (eg CPU fan) in there. The plastic figurine I keep on top of the case hasn't melted yet so, so so far so good...

Posted by:

16 Aug 2013

For my laptops, I've used laptop legs, little folding legs that stick on the bottom of the case & elevate it for better intake airflow. Similar to the folding legs on a keyboard.

Posted by:

17 Aug 2013

Thanks for the insightful article. I like your temporary fix for your heat problem.
I had a similar problem when the fan on my GPU failed. I took an extra 80mm fan and loosely strapped it on with zip ties so that it would hang approx an inch below the graphics card. I then plugged it into the motherboard for a constant power supply and viola! Problem solved.
The extra loosely hanging wires I tied up with another zip tie.

Posted by:

18 Aug 2013


"{. . .]and sometimes is accompanied by a small cloud of dust."

THIS is a sign that your comptuer could use some cleaning before it's too late. I drive around in the North Central deserts of Nevada doing research and when I SEE dust, I know it's time to get out that "can of air" (I often just have a SMALL heavy duty compressor to keep my tires inflated and using a *GOOD* HEPA filter) blow it out using low pressure - which can be a couple of times a week depending on how open I keep my windows or how much wind is blowing - it's that stuff that will eat up or 'burn out' your comptuer. My last comptuer lasted until some online company tossed out some file trying to 'fix' a simple problem that forced me to buy a new comptuer -- about 13 years. THAT is what a clean comptuer can do for you.

Watch the dust when the fan starts up, it's telling you it's time to pull the case and just blow a LITTLE air through it to keep it clean. A good analogy is the buried BBQ pig -- The 'dirt' you use to bury it is the dust, your computer is the pig.

SO NO SOLUTION OTHER THAN THROW MORE AIR AT THE PROBLEM? No small, simple liquid or gas cooler? I mean, Jezzz, even when I lived without power during a graduate program, I used pipe and tubing to keep about 200 gallons of water hot by simple convection heating of some of those metal drums!

We use 21st century technology and stone age technology to cool it?

Posted by:

25 Aug 2013

I use MBAM and update & scan with it on a regular schedule.
I surfed to the "SpeedFan" site and clicked on the proper "Download." Then I went to the "Core Temp" site (both www.almico.com...) and got the message that the latter does not exist. Then when I ran MBAM, I was told that MBAM had quarantined _SpeedFan_!!! I have uninstalled it. Could be a glitch, but I am **not** taking any chances so I uninstalled SpeedFan and won't try for Core Temp again. I'll investigate alternate routes. Safe than sorry. Just my experience. Yours evidently was quite different. Thanks for posting the article anyway.

Posted by:

29 Aug 2013


Core temp is not from almico.com, its from alcpu.com. Differrent site, different makers. And believe me your MBAM is wrong, its false positive. Both program are ok to use.

Posted by:

22 Nov 2013

I downloaded this program but really don't know how to use it. Is it monitoring my temperature on an ongoing basis and will it pop up a warning if my computer is getting too hot? Or, do I have to open it to get the readings if I suspect something is wrong?

Posted by:

Bob Bowen
22 Nov 2013

Speccy by Piriform (free) gives me all the temperature readings I need: CPU, Graphics Card, Hard Drives & Motherboard.

Using an old Mecer XP tower, I had a 64 bit ready PC for Windows 7 built in, using an ASUSTek Inc MotherBoard P5P43TD (28 degrees C); Intel Core 2 Quad Q8200 @ 2.33 GHz CPU (38 degrees C); Nvidia Graphics Card GeForce GTS 250 (35 degrees C); Two Seagate HDDs 500 GB = Local C:\ (32 degrees C) and D:\ (31 degrees C).

Everything ran too hot, so I added two EXTRACTOR, 1200 RPM silent fans, to the side panel, cutting squares of the panel out, to expel the heat, which brought the temperatures down to those given in brackets, and my PC has been running all day today. Of course, the tower must still be cleaned every six months or so of dust and fluff.

It seems, in my view, better policy to expel the heat rather than blow in more air, which works to advantage on hot days.

Thanks for the article Bob.

Posted by:

Nicolo Gonzalez
25 Oct 2014

Despite warnings above, I still fell for the misleading add that says "download" for Speedfan. And I'm suppose to be a computer expert. Kind of insulted why they would do that. But then again, I don't think they have much control over what kind of ads they put on their website. Or do they???

Be very careful

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