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Overheating event brand new 2020 iMac 27 inch 3.3 GHz

Overheating event - brand new 2020 iMac 27 inch 3.3 GHz. iStat Menus gave 30 or 40 warnings that CPU one through six overheated, greater than 92°C for 10 seconds. That’s pretty close to boiling at 100°C. The Mac was just streaming some radio content, smooth jazz and screen saver, or possibly the screen was blank as I was not at home at the time. I came home with a message that the computer restarted because of some panic event asking whether to send to Apple. I did but I suspect they’re not interested on doing anything for the Intel iMac anymore, even though this one is brand new.

I still have two months where I can return it for a full refund, and after looking at some videos of how the 24 inch Apple silicon iMac’s are cooled and four chips are placed into one , with two small fans on each side, instead of one large fan that this iMac has. And I looked at the history on iStat Menus and there was a very large spike at 9:04 through 9:15 AM this morning and I was at work at 8:30 AM. Why would it overheat to such an extent that the computer shut down? Is there a known problem of overheating with this model?

I’m concerned and thinking of returning it and wait for the release of the 27 inch iMac. I suspect with the configuration I need for LogicPro it will be close to $3000. I got a deal on this one at $1399 at Costco during a five day sale. I got a thunderbolt 4 LaCie, and thunderbolt 4 G-Drive (USB-C), and a OWC hub that gives you three more thunderbolt connections; however, this iMac I understand, although it has two thunderbolt ports it’s a shared port and if running both of them the bandwidth is cut in half. Why would they do that?

Just looking for a what folks are thinking the best course of action here. Returning, and wait for the new iMacs which I’m leaning towards doing, or keep this one at such a great price? I probably could hunt down the source of that spike in heat which lasted just a short few minutes going from 40°C to 92°C and back down again. I have two other iMacs,, 2011 and 2014, and they’ve never got so hot.

Best, Seth

iMac 27″, macOS 10.13

Posted on Mar 3, 2022 6:00 PM

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Question marked as Top-ranking reply

Posted on Mar 4, 2022 3:47 AM

Hi Seth77


The overheating while sleeping only affected Intel desktop Macs running Monterey, I'm not aware of any overheating issues with Big Sur.


As you are running Big Sur then don't upgrade to Monterey just yet.


There are multiple reports around the forum of problems on Monterey with attached LaCie drives on Thunderbolt and USB not allowing the Mac to sleep, the drives continually spin-up and shut down. Add to that the numerous reports of Bluetooth devices not staying connected in Monterey then it is probably better to wait for Monterey 12.3 if you want to upgrade.


If you do upgrade to Monterey and then decide to revert back to Big Sur then it is not straight forward, especially if you have a photo library because Monterey uses a different format for the photo library and it is unreadable by Big Sur therefore you need to keep separate backups of the photo library before upgrading to Monterey if you anticipate rolling back.


The other issue that arises when reverting back from Monterey to Big Sur is that local Mail folders are not restored automatically from a Time Machine backup.

The mail folders and contents are not lost but it requires manual extraction from the Mac library after a restore, plenty of information on how to do this on the web via Google search.


If this overheating issue was an everyday occurrence on Big Sur then it might be something to be more concerned about but a one-off event, not sure that much significance can be read into that.


For all macOS's it's a good idea to reboot fully at least once a week.

Although macOS is very stable it is not immune to memory leaks caused by malfunctioning Apps and left unchecked these will eventually pull the OS down, or cause other random problems to appear.


If you leave your Mac powered up and just asleep when not in use then you might expect a few random OS crashes, schedule a weekly shutdown and restart to help prevent these sorts of issues.


Finally, if your Intel based Mac (the only ones I have plenty of experience with) are ever shut down as a result of a power supply outage then always carry out a SMC reset and a Safe-Mode boot after power is restored.

We have plenty of experience with our faculty Macs that show a power outage while Intel Macs are in use often leave the machines with corrupted SMC configuration and damaged system caches.

A SMC reset and Safe-Mode boot should repair those issues that would otherwise persist despite a normal shut down and restart.


Will.

Similar questions

11 replies
Question marked as Top-ranking reply

Mar 4, 2022 3:47 AM in response to Seth77

Hi Seth77


The overheating while sleeping only affected Intel desktop Macs running Monterey, I'm not aware of any overheating issues with Big Sur.


As you are running Big Sur then don't upgrade to Monterey just yet.


There are multiple reports around the forum of problems on Monterey with attached LaCie drives on Thunderbolt and USB not allowing the Mac to sleep, the drives continually spin-up and shut down. Add to that the numerous reports of Bluetooth devices not staying connected in Monterey then it is probably better to wait for Monterey 12.3 if you want to upgrade.


If you do upgrade to Monterey and then decide to revert back to Big Sur then it is not straight forward, especially if you have a photo library because Monterey uses a different format for the photo library and it is unreadable by Big Sur therefore you need to keep separate backups of the photo library before upgrading to Monterey if you anticipate rolling back.


The other issue that arises when reverting back from Monterey to Big Sur is that local Mail folders are not restored automatically from a Time Machine backup.

The mail folders and contents are not lost but it requires manual extraction from the Mac library after a restore, plenty of information on how to do this on the web via Google search.


If this overheating issue was an everyday occurrence on Big Sur then it might be something to be more concerned about but a one-off event, not sure that much significance can be read into that.


For all macOS's it's a good idea to reboot fully at least once a week.

Although macOS is very stable it is not immune to memory leaks caused by malfunctioning Apps and left unchecked these will eventually pull the OS down, or cause other random problems to appear.


If you leave your Mac powered up and just asleep when not in use then you might expect a few random OS crashes, schedule a weekly shutdown and restart to help prevent these sorts of issues.


Finally, if your Intel based Mac (the only ones I have plenty of experience with) are ever shut down as a result of a power supply outage then always carry out a SMC reset and a Safe-Mode boot after power is restored.

We have plenty of experience with our faculty Macs that show a power outage while Intel Macs are in use often leave the machines with corrupted SMC configuration and damaged system caches.

A SMC reset and Safe-Mode boot should repair those issues that would otherwise persist despite a normal shut down and restart.


Will.

Mar 3, 2022 8:14 PM in response to Seth77

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. 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 How to use the Add Text Feature When Post… - Apple Community



Mar 4, 2022 12:21 AM in response to Seth77

Hi Seth77


Addressing the overheating issue alone, beside the etrecheck that rkaufmann87 has asked for, make sure that you are running OS Monterey build 12.2.1, which included a specific fix to address overheating during sleep on Intel based Macs.


Would be interested to know which browser you were using to stream, a few folk were recently reporting runaway memory consumption until system crash with Chrome when multiple tabs open.


Will.

Mar 4, 2022 1:15 AM in response to Will_G_Astro

I’m on Big Sur currently and safari what is the browser I was using to stream some smooth jazz while I was gone.

just saw your replies early this morning as yesterday was my birthday. I have the app etrecheck, is it necessary to update to Monterey first? Or should I run it with the current system that causing the brief episode of overheating. Greater than 92°C for 10 seconds is definitely too hot, yes? The history from iStat Menus reprieve large spike for a few minutes and then back to normal again, after I assume the computer shut down and restarted automatically, as I have it set in system preferences.

Thanks so much for the replies from both of you! Best, Seth

Mar 4, 2022 1:23 AM in response to rkaufmann87

I do have EtreCheck, and have uploaded results here once before, on one of my other iMac’s.

As the other persons stating Monterey addressed such a problem of overheating, but I have not heard this before. Should I update to Monterey from Big Sur, or run the check and upload results on the current system where the problem is occurring, so we might discover from the check what the problem is.

iStat Menus show the very brief spike from the mid to high 30°C, A brief spike just above 90°C and notices greater than 92°C sent from iStat Menus coming from every one of the six CPUs for more than 10 seconds, then assume the computer must’ve shut down and automatically restarted as set in system preferences. One my return home I was greeted with one of those a problem occurred with your Mac and shut down from some panic event and asked if I wanted to send the results of the log to Apple. I haven’t seen one of those in sometime. I might mention that I have not done anything to this iMac except to upgrade from Catalina to Big Sur. Best, Seth

Mar 4, 2022 4:05 AM in response to Will_G_Astro

Thank you so much for your very succinct and organized reply. It was my thinking as well to stick with Big Sur for now and see if I get another overheating event. It was very brief and seen as a short spike in iStat Menus’ history. And yes, you’re correct I have a new LaCie Thunderbolt 4. that connects to the 2020 iMac. The blue iridescent light blinking off and on intermittently, and I wander over to see what’s going on, but nothing is going on.

, I’ll wait and see how it goes and I’m wondering if I should return that drive as I just received it recently and can return it to Amazon. They G-Drive seems to be running perfectly without a hitch and it does not light up unless it’s being accessed. But LaCie keeps Lighting up intermittently without anything going on and I’m sitting watching TV.

Is there a known problem with this drive, or is it a problem with the macOS?

I can still return it to Amazon for a full refund.

Best, Seth

Mar 4, 2022 5:29 AM in response to Seth77

Hi Seth.


Our experience here with recent LaCie Big Dock drives (in raid configuration) has not been that great with several external power supply brick failures that destroy the Big Dock electronics.


I can't comment on the smaller LaCie single drives as we have never used them here.


Most of the recent comments on the forum relating to issues with LaCie drives starting up and shutting down spontaneously seem to suggest the problem is an incompatibility between Monterey and certain LaCie drives but really the information is too vague to begin pointing the finger at one or the other, or even be sure that the problem originates with the drives and whether this is confined to the Apple Silicon Macs or both Intel and Apple.


Some of the staff and students here use personal G-Drives when off site and they have not reported problems as far as I am aware.


If you have a Time Machine backup configured then the external drives(s) will startup every hour, even though the drives are specifically excluded from the Time Machine backup settings. This is a Time Machine & Mac thing, it needs to start up all attached drives to confirm what drives are physically connected before deciding whether they should be backed up or not.


It's possible that the LaCie drive is signalling that the drives Thunderbolt or USB port has woken up while the G-Drive only signals physical disk access, we have no information on that aspect of the drive(s) operation.


Will.

Mar 4, 2022 9:30 AM in response to Will_G_Astro

I did just set up the LaCie to be the time machine back up, so that explains its behavior. I have another LaCie on my 2014 iMac and it’s been working perfectly for the last eight years, never a problem and it’s connected to thunderbolt two. It’s not a time machine back up but use with LogicPro, and use a Seagate 8 TB for TM back up, which has been faithful, although for some reason I don’t have a lot of faith in it.

I’ll do the check on the 2020 unit sometime today, or I might wait to see if it repeats itself and perhaps it was just a fluke. It is a bit disturbing however, as I’ve never had a Mac shut down from overheating and restart and get about 40 warning from iStat Menus CPU 1 was over 92°C for over 10 seconds, CPU 2 was over 92°C for more than 10 seconds, etc.

Mar 5, 2022 9:13 PM in response to rkaufmann87

Waiting for a day off, Monday so I can do the analysis. For now I have an overheating event on my 2014 iMac and it shut down. Again, 92°C for over 10 seconds relating to the CPU’s. I never had an overheating problem before even when the optical bay fan went out on the 2011 iMac for a few weeks before I got another one to replace it, it did not overheat. It seems when I installed TG pro, is when I started having these events. However I did use a Dyson vacuum to clean out as much dust as possible since it is over 10 years old, and I use some canned air to blow behind where the HDD drive, which. is behind her motherboard.

Is there any known issue with TG Pro which has an option to override the systems activity to increase fan speed which never changed on the 2014 iMac. It was always around 1200 RPM. I’ve always been using i-STAT menus for years, never an overheating issue. I’m wondering if I caused a problem vacuuming out the ports on the bottom at the back of the 2011 and 2014 iMac’s. I think I’m hearing there seems to be an issue with the 2020 iMac overheating? I’m not sure what I should do at the moment, but I can’t do too much until I have a day off which will be Monday. Why do thousand 11 iMac also had a shut down issue but it did not seem to be related to overheating, especially with three fans are functioning, except the hard drive fan seems to spend a lot of time at high 2000 to 3000 RPM, and in the past it was always around 1200 RPM. I use some canned when I had it opened up and some dust came out but not very much. I couldn’t get to the hard drive fan which apparently is behind the logic board in the middle, and I wasn’t about to mess with that. I’m concerned I may have candy or some dust into some clumps in there somewhere. There’s a function on TG pro to blast all the fans in an effort to blow out any sense adhere dust within the chassis. I haven’t tried that yet

Best, Seth

Mar 6, 2022 4:15 AM in response to rkaufmann87

To all those that have assisted and given their help in this overheating and very high RPMs of the fans in my three iMac’s, I have found the solution, which might be helpful to others. Many had recommended a few apps to control the fans on their iMac. However, Macs fan control, and TG Pro, one or both were the culprit of my fans RPM going all over the place and getting very high temperature readings, and even shutting down my computers. I completely eliminated both of these apps and all their orphan files, which they were many, using Find Any File. Find Any File I have use for nearly a decade and is a central tool in finding orphan files that are left behind when you delete an app and you think all associated files are also being deleted as many show up asking if you want to remove all of them. Well, it does not. There were over a dozen orphan files that Macs fan control left behind by crystal idea, the same for TG Pro which I paid for. Deleting all of these files for both these apps, which were very persistence in repairing until I manage to eliminate all orphan files.

All three of my imac’s are now running 900 to 1200 RPM as they had been previously and all temperatures are in the 30°C - 40°C. The one app that I have used for nearly a decade is now showing everything back to normal, iStat Menus.

This causes me to wonder if I was getting spurious temperature readings from the sensors making me believe I had to control the fans so my computers would not be overheating. I would hate to think there are those that would really do something like this to make one believe their app was essential? How do you explain all of my three computers now are running the fans at 900–1200 RPM, where before they varied 2000 to 3500 RPM, and a minute later would be down to 1500 RPM, then 3300 RPM and getting temperature readings 70°C to 90°C at times. I had removed all settings for these apps to control the fans, so why were my fans going wild all over the place as well as the sensor readings for temperature? After complete removal of these two apps, specifically the orphan files found by Find Any File did these wild changes in fan velocity and high temperature readings disappear? Now with the same software in idle mode running, which are my screensavers showing images from my photos library and Time Machine. Everything is back to normal after deleting these two apps and all their orphan files. It wasn’t until I deleted the orphan files did things return to normal. Again thanks to all. Best, Seth

Overheating event brand new 2020 iMac 27 inch 3.3 GHz

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