Upgraded to mountain Lion Heating issues

How recent was the upgrade? Upgrading takes a lot of power and after the update spotlight will index the whole computer and other processes will occur which require a lot of power, which ultimately generates a lot of heat.

I have this issue as well. After upgrade, my iMac 3.06 Core 2 Duo is excessively HOT!

I can hear and feel a motor ( hard drive? ) running constantly on the back of the machine, directly above the Apple logo.

The machine get frighteningly hot.

same here. something is heating the poor macbook (late 2011) up 😟

your macbook not in the support list ?

I am experiencing the exact same issue. My late 2010 iMac is on fire: I can't touch it comfortably for more than a few seconds... Sitting in front of it is miserable. The sound is painful. Activity Monitor is showing nothing but Chrome eating up 0.56% of CPU usage, everything else is barely touching the processor(s). 3.34 gigs of 8 free. Disk activity is showing crazy amounts of red spikes every few milliseconds... I am not doing anything disk intensive, nothing at all.

I am installing 10.8 on a late 2011 MacBook Pro now to see if I can duplicate this issue on another machine.

My iMac, however, is suffering greatly with this update. I am worried.

Edit: Mountain Lion was cleanly installed on the iMac's internals. A Time Machine backup migration was performed after the installation.

How long ago did you guys upgrade?

My Air 2011 also ran excessively hot after the upgrade. It did this for about 2 day and had me concerned. But today it's been on non-stop and has stayed cool.

I updated the iMac on Friday. The installer denied my startup disk so I did a clean install. This was the beginning of a series of headaches not relevant to this discussion. Ignore me.

Apropos: It seems to me that the problem might be getting better already. The thing was on fire yesterday and today leading me to search for commiseration. I was sincerely worried about the hardware. Though after a walk around the neighborhood tonight, I can touch the body of the computer again without serious issue, leading me to think I am experiencing a set of anamolies.

I'll keep my eye on it and test out this new install (upgrade-in-place) on the MacBook and hope for the best.

Simply learning of your experience helps ease my concern. Thank you for sharing your experience!

The iMac is back to being untouchably hot in ~20 minutes of use--that use being nothing but casual web browsing. Methinks there is a problem.

However, the MacBook Pro seems completely fine.

Not that anyone is asking, but the Nexus 7 is perfect 😉 weathering all of this without care.

I have this heating problem in two Mountain Lion installations.

In both cases, Activity Monitor shows mdworker using nearly 100% of CPU activity in short 1-2 second bursts.

I suppose that this is Spotlight indexing the drive after a new installation, but this having been going on over three hours now, I wonder if it is normal and expected behaviour.

No wonder my iMacs' temperature is higher than normal.

Something odd : in Lion, indexing activity and remaining time were shown in the Spotlight icon and its search window.

In Mountain Lion, no activity whatsoever is reported by Spotlight itself, eventhough Activity Monitor relates it to Spotlight indexing (mdworker).

Another new "feature" in Mountain Lion ? ...

YM

what is a Nexus 7?

Here is some onfo for those that need it

mdworker is short for ‘metadata server worker’ and if you’re still confused don’t feel bad. mdworker is basically the core technology behind Mac OS X’s awesome search engine Spotlight, it spiders meta data from your Mac and its files and creates a readable index so that you can find things practically instantaneously via Spotlight (command-spacebar). Here are some common questions and answers regarding mdworker, inspired by my recent switcher friend Daryl, who tweeted me asking why mdworker is taking up so much CPU.

What is mdworker?

As mentioned above, mdworker is part of Spotlight, which is basically a search engine for your Mac (think Google but locally, for your own files).

mdworker is slowing down my Mac with 60% CPU usage!

Yes, mdworker will sometimes cause your Mac to be slow and have high CPU usage, this is totally normal. You should just let it run until it’s finished, and CPU usage will be back to normal.

How long does mdworker take to finish?

This is entirely dependent on the last time that your Mac filesystem was indexed and the amount of new files since indexing. If you just plugged in a loaded external hard drive, expect it to take a while. 15 minutes to well over an hour are not uncommon amounts of time for mdworker to run.

Should I kill mdworker? What happens if I kill mdworker?

No you shouldn’t kill mdworker, because it’s doing you a service by indexing your Macs contents. If you do kill mdworker, your Mac filesystem will not be completely indexed and it’s searchability will be greatly reduced until mdworker runs again and completes a full indexing. There is no serious problem with killing mdworker, it’s just not recommended.

How can I stop mdworker or disable mdworker?

Since mdworker is part of Spotlight, you’ll have to disable Spotlight to disable mdworker. Again, this is not recommended, but if you want to disable mdworker here’s a how-to guide:
How to Disable Spotlight

What about mds? Is this tied to mdworker?

Yes, mds is the parent metadata server that runs the child process mdworker, the two usually run concurrently. You can read specifically about mds and Mac OS for more information.

I have read lots of reports of spotlight taking an age on new installations of ML.

My iMac has been burning up for almost 72 hours. mdworker isn't logging tasks of any importance as of this moment.

I've been slaying this MacBook Pro for hours and she isn't sweating. The iMac, though, my main machine, is kinda hurting without any evidence of a problem via Activity Monitor. Would you have a recommendation of another tool I might utilize to examine why all fans are spinning and the computer is baking with temps available to the seated user?

Edit: I should add, I am getting sent back to the login screen sporadically during active sessions after a brief (~30 sec) blackout. Not reproducible, I have no idea besides hardware problem.

One work around until they release the Mountain Lion patch updateis install smc Fan Control. Basically by defauly the fan runs at 2000RPM and this allows you to increase that minimum. I have set it to 4000RPM and there is very minimal audible difference and it is bringing the core temparature down for the most part all of the time. You can go higher but I think thats overkill.

smc Fan Control is free, after you install it, it resides in your notification area in the top right (this is where you can change settings etc)

Hope this helped you as I know personally how annoying these overheats can be.