View Full Version : Mountain Lion running hot?

Jul 28, 2012, 12:33 PM
Has anybody noticed an increase in their CPU temperature since installing Mountain Lion? It seems like mine runs at least 5° hotter (and sometimes even more) since I installed Mountain Lion on launch day. For example right now my CPU is running at 52°C, which isn't anything to be concerned about I realize, but it's still at least 5° hotter than it would normally be right now.

Anybody else notice a difference?


Jul 28, 2012, 12:37 PM
It's running hotter for me too. Perhaps it might be addressed in a future patch.

See attached.

Jul 28, 2012, 12:46 PM
I noticed that sometimes some applications (Safari, Mail, Finder) take a significant amount of CPU % (up to 10%) when doing nothing. This, in turn, has an effect on the whole machine temperature. Restarting them (and, in the case of Safari, going back to the page that was open before) brings them back to 1-2% of CPU and the machine cools down. Weird.

Jul 28, 2012, 12:56 PM
yeah my macbook is burning up running it. Not keen on this!

Jul 28, 2012, 02:52 PM
I haven't noticed.

Jul 28, 2012, 03:01 PM
Macbook air and i'm getting cooler temps and longer battery life.

simple browsing i'm chilling at 55ºc

used to be 60'ish

Jul 28, 2012, 03:26 PM
My 2009 MBP is noticeably hotter, especially when charing, and the fun runs more than it did with 10.7

I haven't taken the time to check the temps, but I have checked activity monitor and did not see anything unusual about any of the active processes.

Jul 28, 2012, 03:52 PM
I've found that my Mac runs hotter than before using the dedicated graphics, but actually cooler when using the integrated graphics. A little strange.

Jul 28, 2012, 04:10 PM
Yes, I'm noticing it's running a little warmer than usual.

Bob Coxner
Jul 28, 2012, 04:51 PM
2011 base 13" MBA. Seems a bit cooler for me.

Jul 28, 2012, 04:57 PM
Before ML my CPU would run at about 50 degrees C with Chrome open, now it can hit anywhere between 60 and 80 degrees C. ML definitely runs hotter than Snow Leopard.

Jul 28, 2012, 05:07 PM
Same here - prior to ML install, almost NEVER heard the fan unless I had a few apps open. Now, it seems like the thing is running all the time. I do have a Speck Clear Case on my MBP 13 and experiementing right now with removing that to see if that helps with the heat.

I thought it might just be me but seems like others are noticing the same thing. I have checked out my Activity Monitor and nothing out of the ordinary appears to be occurring. Hope a patch is on the way to address this.

7/30/12 Update: Turns out I solved my problem. I had a process called bash running and I really didn't think much of it at the time because it was only using about 6-7% of the CPU. On the Apple Community forum I found a thread where someone indicated that this "bash" process was hosing up their CPU even though the number wasn't high like 99%. This process is associated with Send to Kindle for Mac which I had on my computer.

I removed this app and just like that - my temp went from 88-90C to a steady 45C and my RPMs went from 4500-5000 to a steady 2500. I am so glad that I found out what was causing this issue and now, my baby is back to the way it was before. Just wanted to pass this information on in the event it might help someone else.

Jul 28, 2012, 11:47 PM
Well same here! i just changed cpu thermal compound on my MBP 13 mid 2010 3 days ago while i had Lion, and my idle temps were 40-45 C even 38 C, and today installed Mountain Lion and now is running hot, idle 50-55, that isn't good. now i cant have it on my lap for a long time without sweat! :D haha. i hope they fix this soon!

Jul 29, 2012, 07:16 AM
I'm noticing the CPU temperature increase on my MBP 2010 as well. It went from <43C to >50C (when idle). And I think this increases the battery drain because the notbook doesn't last as long as it used to when I was running Snow Leopard on it.

Jul 30, 2012, 07:54 PM
Mackbook 5,1 (ie, 2009)

Definitely running hotter. No doubt about it. Just sitting idle with all the apps closed and the fan will kick on. Previously, the fan almost never ran. 52C at the moment with only Safari and dashboard running.

Jul 30, 2012, 08:13 PM
I know this is a stupid question, but how do you check the cpu temperature?

Aug 3, 2012, 07:03 PM
I know this is a stupid question, but how do you check the cpu temperature?

Download the iStat widget for your dashboard.

Aug 3, 2012, 11:19 PM

Aug 20, 2012, 06:40 AM
I bought Mountain Lion on a few days ago and yesterday since the first time that I bought my MacBook Pro in the beginning of the year had it not once shut down on its own from heat, before it shut down it was constantly going 65+ until it just shut down! I feel like putting back Lion. This is a 2009 unibody model.

Mar 26, 2013, 12:45 PM
Even with a few apps and a single vm running, I am running between 75ºc and 95ºc constantly. The only time it gets cooler is when I first start it up, then bam, right to 75ºc it goes and stays there until I start up more apps and vm's and the fans kick in until it gets back under 99ºc.