Why is my MacBook Pro suddenly running hot?

This is weird, but all of a suddenly my MacBook Pro is running really hot and the fan keeps turning on. Not a big deal, but I'm used to it being quiet and smooth without ever even being aware of its temperature. Is there a power supply problem, as my Dad suggests, or is it something else going on? I'm just afraid that my Mac is about to die and that'd be a disaster!

Dave's Answer:

First things first: you need to ensure that you always have a reliable backup strategy in place and that it works. Are you doing that? If you aren't, then I will share that I'm a big fan of my Apple Time Capsule. Hook it up and you can literally forget about it: every time you're in the same place as the device, it'll automatically start backing up, thanks to the magic of Time Machine. As I write this a 1TB unit that has lots of other features runs under $300, which is nothing compared to the cost of losing your data!

Now, let's look at your heat issue. While there are a number of reasons that your Mac can be heating up, including some scary hardware problems - like a failing power supply - that would mean you need to take it in for repair ASAP - it's more likely that you have a wedged process that is causing the CPU to run full-tilt and heat up. Yup, it's like your brain: if you use it a lot, your computer gets a bit of a headache. :-)

It's not easy to find, but Apple actually includes a utility with Mac OS X that lets you find out if you have a runaway process of this nature. I think that's a good place to start!

The app is called "Activity Monitor" and you can find it in Applications --> Utilities. Launch it and you'll see something like this:

You can see what processes you have running, what's touching your disk (another possible cause of overheating, btw: a process that's thrashing the disk (really, that's the tech term for it) and causing the drive to heat up), and lots of other interesting information about how your computer is doing.

If you're having problems with insufficient memory, you can also see what apps are eating up your RAM too. Notice in this screen shot that Chromium (Google's developer version of Chrome) is using 192MB of RAM, along with its helper apps that are eating up another 100MB or more. Fortunately I have 4GB of RAM so there's plenty of space (you can check how much RAM you have by choosing "About This Mac" from the Apple menu, btw).

We're interested in CPU usage, however, so notice on the column headings there's one that says "% CPU". Click on it and if you now see those apps that have 0.0 on top, click on it again to change the sorting order.

Now you should see something like this:

Watch it for a few minutes. If you have an app that consistently is at 90% or more (as I have here with GrowlHelperApp) then you need to quit this application and see if it helps your computer cool off and slow down. To do that, click on the name of the app, then click on the red "Quit Process" stop sign icon on the top.

You'll be asked:

Your two choices are "Quit" or "Force Quit". Do the former. If it doesn't work, then do a force quit. The difference is that a regular "quit" lets the application shut down gracefully, saving state files, deleting any temporary or scratch data, etc. A force quit is the operating system ripping the virtual heart out of the app without mercy. Yeah, it's brutal and you should only use it as a last resort (unless you're a fan of that sort of thing).

I'm betting that your computer will cool off and you'll be relieved not to have a hardware problem.

Now, the question is: why is the app running out of control? Sometimes it's just a random occurrence and it won't happen again for months, if ever. In other cases, something's changed and the app has become unstable for some reason, as is the case with Growl on my Mac. In that case, make sure you have the very latest version of the software, and if it's still a problem, drop an email to the developer letting them know what you're seeing and check to see if they have any suggestions.

Good luck, I hope that helps your MacBook heat problem as it did mine.

Categorized: Mac OS X Help (Article 9278, Written by Dave Taylor)
Tagged: apple macbook pro, cpu usage, mac os x, memory, ram, troubleshooting
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Comments

I've also found Onyx useful when my machine is running hot when I've been unable to identify what else is going on. I've tried some of the things it does by hand (like repairing disk permissions, cleaning some caches, etc) without finding a fix. But Onyx has fixed the problem multiple times, and I gave them a donation in thanks (as I've bought you a cuppa). If you know what step it is taking that might be the key one, I'd love to know.

Posted by: Winnie Williams at January 25, 2010 6:26 PM

From the purely hardware PoV, you might want to see how dirty the computer is.

Given that they are famous for the vacuum cleaner functions, most computers accumulate dust internally. As this happens, the internal air flow deteriorates. This causes heat build up.

Laptops are less prone to dust because of the lack of open space in the design, but, when it happens, it tends to be more pronounced. This is especially true when the dust accumulation is on or in the heat sink.

Posted by: Chrystoph at January 26, 2010 5:51 AM

oh thank you thank you thank you for this fix recommendation!

Posted by: Annie at February 10, 2010 10:30 PM

Thanks for this!!! My Mac has been running hot for awhile and just figured it was due to use... but my FINDER was using 99% of my CPU! Yikes... anyway, forced quit and within 20 seconds it started cooling off. THANKS!!!!

Posted by: Daryl at September 5, 2010 7:09 PM

Awesome fix. Had a printer firmware taking up 98%! Force quit and computer can sit on my lap again. Thanks!

Posted by: Keith Fung at September 7, 2010 8:03 AM

Hey, thanks for this. I found a Dashboard client running at 89% and within minutes it cooled down. Cheers

Posted by: john Hanson at September 22, 2010 8:03 AM

Thank you so much. Your thread is right on the money. I had an updated Google flash plug-in that was using up to 99% of my CPU. I was really concerned because it was getting so hot and eating away my batter life so quickly. But now my problems are solved. Thank you again!

Posted by: Austin King at November 27, 2010 2:31 AM

thanks. you are a legend!! printer app using 98% cpu. glad I found this before my pro died a premature death. :) :)

Posted by: simeon helme at January 13, 2011 4:41 AM

Thanks!!! The Finder application was crazy. It somehow was killing my battery as well. This just helped me boost the duration of my battery and also stopped the computer from heating up.

Posted by: Zeemin at January 24, 2011 2:15 PM

thank you!!!

Posted by: KBH at January 28, 2011 7:54 PM

ur r great!!! found a printer app thats running 100%...quit it and my MBP cools down instantly....thank you very much!!!

Posted by: cheese at February 1, 2011 12:45 AM

I tried your suggestion (thank you for posting it) but I am still finding it running very hot (149-155F) on the CPU and heatsink A. Right now the fan is running at 2400RPM. I am running a MacBook Unibody OSX 10.5.8, Intel Core 2 duo, 2 gig ram. I am in Tanzania and don't have very good internet access so doing big software updates is very difficult. Any ideas would be appreciated. Right now, when it gets too hot I put it on the tile floor which is cool and it gets better. Thanks.

Posted by: Larry Pepper at March 1, 2011 5:13 AM

Thanks!! Finally the right answer, after searching the entire web.

Posted by: MDO at April 25, 2011 9:11 PM

Thank you so much for this post! My laptop had been running hot and a google search led me here. With you help I located a printer app using 93% CPU, quit the app and 'puter cooled down immediately.

Posted by: Kathleen at April 28, 2011 10:34 AM

Great advise ! Adobe something was using 90 % of CPU and killing my battery. I quit it and the poor Mac cools off within a few minutes. Will bookmark your site and pass it on.

But why the hell does Mac let those apps take control just randomly of its machine ?!

Posted by: Trang Dao at June 2, 2011 12:36 AM

Dave - Very helpful!

Posted by: John Haydon at July 8, 2011 8:22 AM

Thanks for the helpful advice!

Posted by: sher at July 10, 2011 1:12 PM

oh my gosh, this totally worked. it turns out there was an adobe thing running without me knowing!

it was crazy how hot my laptop was getting. thanks!

Posted by: cathy at July 18, 2011 11:15 AM

thanks! this worked! seems like i had a failure connecting wirelessly to my printer and this fixed it! I appreciate this post!

Posted by: jess at July 29, 2011 7:01 AM

Turned out my MacBook Pro was running extra hot because the battery was almost dead, and wasn't charging properly when the computer was plugged in. New battery (thank you AppleCare) and it is cooler. Still pretty warm, but not dangerously hot.

Posted by: Betty at September 27, 2011 2:03 PM

Oh man thank you so much! I've been looking everywhere for a solution for my problem andhere I finally found it. It was app related to my printer. Thank you a lot for the help. I just wish I found this earlier! I hope I didn't already damage my Mac too much! it's been around a year that it's heating up like this!

Posted by: Paul at October 2, 2011 9:58 AM

I wanna thank you again for this post! I just can thank you enough!

Posted by: Paul at October 2, 2011 4:29 PM

THANK YOU FOR SAVING MY LIFE!!!!!!!!!!!!!!!!!!!!!

Posted by: Kasey Brooks at October 12, 2011 12:13 AM

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I do have a lot to say, and questions of my own for that matter, but first I'd like to say thank you for all your efforts on this Web site by buying you a cup of coffee!

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