9 Replies Latest reply: Sep 26, 2012 8:54 PM by rez7
Nat Harari Level 1 Level 1 (0 points)

Hey everyone,


First off: Upgraded to Mountain Lion and I absolutely love it. I'm running on a December 2011 MacBook Pro Unibody 15", 8 Gigs ram, i7, SSD 256 drive (Apple). It had Lion installed when it came, obviously.


Now that I upgraded to Mountain Lion, it's running several degrees celcius hotter than before, after a couple of hours of using it. I figured I'd give it a few hours to do its search database thing etc...you know, let the system stuff in the background settle down, but it's still running very hot.


Is this something which eveyrone else has been experiencing? I've got two methods of checking the tempurature: iStat Nano on the Dashboard (which I don't use for anything else...) and smcFanControl which sits in my menu bar. Both give me the same tempurature and it's running literally about 5 to 7 degrees more (or sometimes even spiking at 15 degrees more for a few seconds) than before.


Just wondering if I'm the only one? Should I be patient and give it a day or so? Any tips?





MacBook Pro, Mac OS X (10.7), Time Machine, External Drive
  • fordfiction Level 1 Level 1 (0 points)

    You're not the only one. My 2011 13" Macbook Pro is running significantly hotter as well. The temp is up about 10 degrees, and my fan, which has always been quiet, is now running at a constant low whir, but grows much louder during normal app use.

  • chockswahay Level 1 Level 1 (0 points)

    I have this too!  My Macbook Air 13" used to run at about 42c now it runs at around 58c!  I don't know if the previous fix will work (see my other entries)

  • softwater Level 5 Level 5 (5,370 points)

    You're right that in the first few hours ML will be busy in the background running certain processes like indexing Spotlight and Time Machine.


    You can see if these are still indexing by looking at the menu bar. Click on Spotlight - if you get a progress bar saying its indexing, just leave everthing alone till its finished. If you look at the TM icon, it should be slowly circling if TM is still indexing. Again, click on the icon and see what it says.


    If these seem to have completed, check in Activity Monitor.app (Applications/Utilities/Activity Monitor.app) as to what is using up %CPU time. If you see kernel_task is running wild (+80%) , try a PRAM reset. To do so, folllow this procedure:


    1. Power down the machine.

    2. Locate the following keys on your keyboard in preparation for Step 4:

    ‘command’ – ‘option’ – ‘P’ – ‘R’

    3. Press the ‘power on’ button.

    4. Immediately – and before the grey screen appears – hold down ‘command-option-P-R’ all together.

    5. Keep them held down until you’ve heard the start-up chime twice. After you release them you should hear it again, and hopefully your Mac will boot up as it should and with the kernel_task process back to normal.

  • magicrevolver Level 1 Level 1 (0 points)

    Mine is the same, I've got a 2009 Macbook Pro and it seems to run hotter with ML.

  • bartlettpsj Level 1 Level 1 (0 points)

    Yup same problem here.  I have Macbook Air 13" June 2012 and definitely gets hotter quicker.  Fans come on sometime now.

  • sid6062 Level 1 Level 1 (0 points)

    Lion I was running about 45-50 C with just firefox running...now with mountain lion I'm running at steady 67 C with just firefox. I checked my activity monitor, firefox...activ monitor, and dock are the three top items there. I have a late 2011 MacBook Pro 15".


    A fix would be great Apple. K? Thanks.

  • chockswahay Level 1 Level 1 (0 points)

    Well, I did an SMC reset and the PRAM reset (although nothing running wild) and my laptop is back to normal


    I have just ran a check against my wifes Macbook (same spec) which does not have ML on it and the two run at very similar temps.  Something I did notice is that the QT videos use less energy and the 'puter runs cooler when watching these (youtube) so all in a result !


    By the way, if you're interested this is a really nice video to watch, not me but I'd love to do that!





  • rez7 Level 1 Level 1 (0 points)

    Good news/bad news kind of thing with the PRAM reset suggested by softwater - cpu and power draw did settle down dramatically but now it takes forever (well about 2-3 minutes) to shut down my 2011 mbp.  I guess on balance this is preferable to an external power supply brick and cpu area on the mb running so hot you could hardly touch them and the fan running constantly to try and keep things cool as well as activity monitor showing significant cpu activity with no user apps running.  Snow Leopard never did any of that stuff.