For some reason the fans in my MacBook Pro (2007 model) seem to run at full speed for no apparent reason, I've been using the "iStats" gem to monitor my temps and fan speeds - what's strange is that the CPU temperature often sits around 40 - 45°C even when the fans are running around the 2000RPM mark - yet occasionally, for some odd reason it decides to boost them up to 5000RPM+. I'll just be happily browsing the web and all of a sudden it decides its time for takeoff...

CPU Temp & Fan Speed, iStats Terminal View

Anybody know a reason or possible fix for this? I've considered using some software to control the fan speed manually though I don't want to do anything that might potentially cause the system overheat.

Any ideas are welcome!

1 Answer 1


Trouble with fan speeds can almost always be solved by resetting the System Management Controller, or SMC.

After performing normal troubleshooting, these symptoms may indicate that an SMC reset could be necessary.


  • The computer's fans run at high speed although the computer is not experiencing heavy usage and is properly ventilated.

Source: http://support.apple.com/kb/HT3964

The procedure for laptops with removable batteries is as follows:

  1. Shut down the computer.
  2. Disconnect the MagSafe power adapter from the computer, if it's connected.
  3. Remove the battery.
  4. Press and hold the power button for 5 seconds.
  5. Release the power button.
  6. Reconnect the battery and MagSafe power adapter.
  7. Press the power button to turn on the computer.

Source: http://support.apple.com/kb/HT3964

  • Thanks for this, I'll give it a shot and see if it works!
    – Kolors
    Sep 2, 2014 at 11:11
  • UPDATE : Fans seem to be working normally, I'll give it a little while to see how things go - fingers crossed that this worked!
    – Kolors
    Sep 2, 2014 at 18:34
  • UPDATE 2 : Fans seem to be much quieter and certainly slower. - Thanks for this!
    – Kolors
    Sep 2, 2014 at 22:05
  • Since this appeared in search results in 2022, here is the updated link to the support page on SMC reset for Intel machines: support.apple.com/en-us/HT201295
    – D. Geren
    Aug 4, 2022 at 16:08

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