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iMac getting very hot

I have a iMac 27’’ from 2010. For some time I have noticed that the computer gets very hot at the upper left corner on the backside. It feels like you could boil an egg there. What is the highest temperature (in Celcius) allowed measured in the CPU?

I have not had any problem with the computer shutting down or any other alarming things.

What symptoms should I look out for?

I have made a reset of SMC.

iMac, iOS 10.3.3, iMAC 27'' 2010

Posted on Aug 22, 2017 1:01 PM

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Question marked as Top-ranking reply

Posted on Aug 22, 2017 11:30 PM

Use Activity Monitor to Kill Runaway Processes


Use Activity Monitor on your Mac

Runaway applications can shorten battery runtime, affect performance, and increase heat and fan activity.


Should the above not prove helpful, then make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.


The rear is the vent for the cooling system, so it does get hot. If the CPU reaches 125ºC the computer will shut down. How hot it gets, otherwise, depends on what you are doing. I suggest you get a utility like iStat Menu so you can monitor temps.

4 replies
Question marked as Top-ranking reply

Aug 22, 2017 11:30 PM in response to jansberg

Use Activity Monitor to Kill Runaway Processes


Use Activity Monitor on your Mac

Runaway applications can shorten battery runtime, affect performance, and increase heat and fan activity.


Should the above not prove helpful, then make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.


The rear is the vent for the cooling system, so it does get hot. If the CPU reaches 125ºC the computer will shut down. How hot it gets, otherwise, depends on what you are doing. I suggest you get a utility like iStat Menu so you can monitor temps.

Aug 23, 2017 2:32 PM in response to jansberg

They are all important but the main concerns would be CPU and GPU temps. You should wait until your computer has been fully shut down to be completely cool. Then turn it on and note down the startup temps. These represent the "normal" baseline temps. These will change over the day but what you are looking for is the so-called runaway program as discussed in the links already posted here. Also, watch fan speeds. The hotter the computer gets above settings in the firmware the faster the fans will go.


If the CPU or GPU are running at 100ºC or hotter that is too hot. Check Activity Monitor to see if any application has gone runaway by checking the CPU% column to display in descending order.

iMac getting very hot

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