Since some time my MacBook is constantly hotter than it used to be, even when not having much CPU load. What could the cause be?

Resetting the System Management Controller (SMC) didn't completely work, I think it has decreased since I reset it but not completely.


Sometimes is is good to reset the SMC.

SMC controls the devices on your computer including the fans.

Intel-based Macs: Resetting the System Management Controller (SMC)

  • Didn't really work. It has decreased I think but not completely. +1 however – stommestack Aug 12 '13 at 10:42
  • Thank you :) how do you measure the temperature? – Ruskes Aug 12 '13 at 10:55
  • You know any temp monitor is only as good as the calibration matrix. With that said, it does not mean you Mac gets hot(er), but how relevant is it. – Ruskes Aug 12 '13 at 11:05
  • I also can feel heat when holding my finger against the left alt key. I couldn't feel it there before. – stommestack Aug 12 '13 at 11:07

Don't overlook purely software usage. If you browse sites with flash content it is not unusual for it put more load on the machine. you mention "not having much CPU load" which implies that the machine is not totally idle. Is it while doing absolutely nothing with machine? Switch to another browser for a while and see if it makes difference.

  • I have a lot of background application which consume 3-10% CPU. But it's weird it's getting hotter than a while back. – stommestack Aug 12 '13 at 12:44
  • I have found that anytime my mac gets hot there are normally some flash being run in a open web tab... sure you did not get new version of browser or flash. AS troubleshooting try close all web browsers for a while and see if heat problem remains. – Joop Aug 12 '13 at 14:20

To kill a problem, you have to see it and then understand it.

For this hunt, I advise to start with the Activity Monitor which is here:

Applications/Utilities/Activity Monitor

Look at what is using the CPU when your MacBook is heating and when it is at a normal temperature. Try starting and stoping your actual programs one at a time and let the system take the time to free all the threads involved and the temperature decrease.

The delay between a hog kill and the fan slow down may be bigger than a minute.

  • It's always heating :/ I will try logging in at the guest account and see if it also heats there, however. – stommestack Aug 14 '13 at 7:30
  • → Jop: is it heating with no session active? – dan Aug 14 '13 at 8:02

Try disabling helpers on your browser (like Avast) which might be working too hard. I had this problem, but I disabled security as needed and it stopped right away.

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