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iMac Overheating

My iMac has been experiencing some strange fan issues. The fan runs noticeably whenever the screen is on, even when no application is being used. And when I start to use any application, even a browser, they quickly ramp up even more. The strange thing is, as soon as I put the mac to sleep, they will cease to run, or at least to make any noticeable noise, within a minute. Any suggestions on what kind of problem this is? I have just had the hard drive replaced (separate issue) and have set the machine up like new, so there is barley anything on it.

iMac 27″, macOS 11.1

Posted on Apr 5, 2021 10:44 AM

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Question marked as Top-ranking reply

Posted on Apr 5, 2021 11:39 AM

/Applications/Utilities/Activity Monitor.app can show you lots of information about what processes are running on your computer and how much memory and CPU they are using. This may be useful in determining why the machine is heating up and what is using a larger percentage of the CPU time. Also, if you are very low on physical memory, the computer may be using Swap space, virtual memory space on the hard drive. This can result in excessive hard drive activity and also cause additional heat. When the hard drive and the CPU are both very active, this will generate heat that causes the fans to kick in faster and louder. Explore around Activity Monitor and see what might be going on with your CPU usage and memory/swap usage. Just a couple of ideas that might help track down what is going on, using a built-in tool that you already have installed on your machine.


Since you just installed a new hard drive, it may be that Spotlight is performing a re-indexing of all your files. This background process can take up a lot of resources, but once it finishes, then things will be back to normal. If you see the mdworker process taking up a lot of CPU, that is Spotlight doing its work. Can you leave the machine running overnight and see if that allows Spotlight to finish the index?


https://osxdaily.com/2009/09/14/mdworker-what-is-mdworker/





3 replies
Question marked as Top-ranking reply

Apr 5, 2021 11:39 AM in response to Ajmjmedia

/Applications/Utilities/Activity Monitor.app can show you lots of information about what processes are running on your computer and how much memory and CPU they are using. This may be useful in determining why the machine is heating up and what is using a larger percentage of the CPU time. Also, if you are very low on physical memory, the computer may be using Swap space, virtual memory space on the hard drive. This can result in excessive hard drive activity and also cause additional heat. When the hard drive and the CPU are both very active, this will generate heat that causes the fans to kick in faster and louder. Explore around Activity Monitor and see what might be going on with your CPU usage and memory/swap usage. Just a couple of ideas that might help track down what is going on, using a built-in tool that you already have installed on your machine.


Since you just installed a new hard drive, it may be that Spotlight is performing a re-indexing of all your files. This background process can take up a lot of resources, but once it finishes, then things will be back to normal. If you see the mdworker process taking up a lot of CPU, that is Spotlight doing its work. Can you leave the machine running overnight and see if that allows Spotlight to finish the index?


https://osxdaily.com/2009/09/14/mdworker-what-is-mdworker/





Apr 5, 2021 11:04 AM in response to Ajmjmedia

Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.


When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again.


For instructions on how to download your EtreCheck report and attach it to your reply to this message please click https://discussions.apple.com/docs/DOC-250000211



iMac Overheating

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