2020 iMac 27” - ? A known problem intermittent overheating, shut down

[Zephar77]

Is there a known problem with the latest 2020 iMac 27 inch having intermittent overheating events while idling? (Only at idle, showing screensaver photos from the photos app). iStat Menus history shows all six cores spiking from 30°–40° centigrade to A sudden 95°C spike lasting a few minutes, then back down to 30° - 40°C again, or shut down Panic event, asking if to send logging of the event to Apple(I’m sure they’ll look very closely at this with Apple Silicon iMacs on their drawing boards). (Nearly boiling point). Although supposedly Intel says this is probably OK, certainly Will shorten the lifetime of this iMac. I don’t understand why there’s one fan still? I noticed Apple Silicon new iMacs have two fans, and my older 2011 iMac has three. My older 2011 iMac runs cool always, but my 2014 iMac with one fan runs 10 to 15°C hotter at idle. And like the new 2020 iMac the fan seems to always be around 1200 RPM no matter what you’re doing. My 2011 iMac three fans change RPMs greatly depending on what I’m doing, as one would expect - seems Apple disconnected the fan from temperatures of the CPU cores to control fan and keep things running cool. Receiving the same thing from my 2014 as with the 2020 iMac, so I suspect there’s been no change in those six years, with one fan? I’m about ready to return it for a refund at Costco. Purchased because they knocked off $400 on some special sale they had for five days on the 512 SSD 3.3 GHz model. Was disappointed with the recent Apple Event only presenting the Studio Mac, Which looks like a jazzed up Mac mini, and a very expensive 27 inch matching monitor for $1600, so your basic entry level would be $3600. And of course you have to get their ram which would cost an additional $400-$600 for runnin LogicPro. Guess we’ll have to wait untill this fall for what we suspect will be the replacement for the all-in-one iMac 27 inch to 32 inch Display?
This is what I did initially: 2020 iMac 27” 512, SSD 3.3 GHz - reformatted SSD and fresh install of Big Sur, then bringing over files and folders from 2014 iMac. 2014 iMac was running same macOS, Big Sur, so there should not have been any issues, and there was not. very smooth transition and no problems for several weeks.
Always been concerned after my 2011 iMac with three fans, and a switch to the newer 2014 iMac with only one fan. Why? Why, and no matter what you’re doing, using logic pro extensively the fan always seems to stay at about 1200 RPMs. Only when the sharp spike temperature from 30°C to 95°C for a few minutes the fan suddenly goes to maximum near 2700 RPM, but only for a few minutes then back down to 1200 RPM. This is occurred three times in the past month or so.
Any input/advice on any of the above would be much appreciated folks. Best, Seth

 

[Fishrrman]

Sounds to me like you have one or more apps or processes that are "running away" and overloading the CPU/GPU while the Mac is [otherwise] at idle...

 

[ondert]

I had a similar issue before on my 2016 macbook pro, turned out it was Steelseries' garbage software.

 

[Zephar77]

Sounds to me like you have one or more apps or processes that are "running away" and overloading the CPU/GPU while the Mac is [otherwise] at idle...

That is what I was hoping for, yet yet activity monitor did not show any process out of the ordinary. However, the event lasted a few minutes and then dissipated quickly. Cannot determine if that’s when the computer shut down or not.

 

[Zephar77]

I had a similar issue before on my 2016 macbook pro, turned out it was Steelseries' garbage software.

How did you track down which software was causing the problem? I suspect that is my issue or problem, but I don’t have any new software that hasn’t been there for years. An update possibly might change the environment. How did you track down what software it was. Activity Monitor?

 

[ondert]

How did you track down which software was causing the problem? I suspect that is my issue or problem, but I don’t have any new software that hasn’t been there for years. An update possibly might change the environment. How did you track down what software it was. Activity Monitor?

When the Mac goes wild I checked the activity monitor immediately and sort all the processes from highest cpu usage to the lowest. Then I saw it there.

 

[wilberforce]

I have stressed my 2020 iMac by fully loading all 16 logical cores of my i7 to 100% by running 16 instances of the "yes" process continuously for an hour, with no issues (fan is of course continuously at max 2700 rpm and CPU PECI at 99C).
Under normal use CPU does not get above 55C and fan is at idle, for 99% of the time. Fan only starts increasing when CPU PECI gets to about 90C, this is completely normal, even though you may "feel" it is not desirable.
If you are saying your fan spins up only 3 times a month, you have nothing to worry about.

 

[Zephar77]

When the Mac goes wild I checked the activity monitor immediately and sort all the processes from highest cpu usage to the lowest. Then I saw it there.

There in lies the problem. It only occurs when I’m gone at work and the computer is idling streaming some jazz music in the background through Safari. I’ve gone through all the apps and done search for orphan files with Find Any File, and deleted all of them as well. I have bare bones applications with the exception of Carbon Copy Cloner, I stat menus, and find any file, application cleaner. Unfortunately activity monitor doesn’t give you a history like iStat Menus. But iStat Menus, well perhaps it does give you up to a 30 day history of GPU activity? But it won’t tell you what it is using that GPU activity unfortunately. Hmm ? Seth

 

[Zephar77]

I have stressed my 2020 iMac by fully loading all 16 logical cores of my i7 to 100% by running 16 instances of the "yes" process continuously for an hour, with no issues (fan is of course continuously at max 2700 rpm and CPU PECI at 99C).
Under normal use CPU does not get above 55C and fan is at idle, for 99% of the time. Fan only starts increasing when CPU PECI gets to about 90C, this is completely normal, even though you may "feel" it is not desirable.
If you are saying your fan spins up only 3 times a month, you have nothing to worry about.

I suspect you are correct, it’s just that it occurs in a very sharp spike seen in iStat Menus for a few minutes and then suddenly back to normal temperature and fan speed, 30° - 40°C and from 2700 RPM to 1200 RPM. Just very strange. The computer was not being stressed, and that is why it concerns me. Something is not right, and I have stressed it, not to the extent that you have, and got temperatures to go up, but the fan always stays at 1200 RPM. I think it gets tripped to max out or be 1200 RPM, and it seems to be 90°C or above. That’s a bit bothersome as well as my 2011 iMac has three fans and they vary greatly depending on what One is doing, and very sensitive to the thermal sensors change in temperature changing the fans speed. It seems Apple took this away, at least with my 2014 behaving the same as my 2020 iMac. I appreciate your input. Seth

 

[ondert]

Wow.. dude my new 5K 2020 iMac with i7 & 5700XT just arrived and mine is running too hot also. It's always between 70-90 celcius degree on idle and sometimes jump to 100 I might return and order another one if they don't sell out at refurbished section.

edit: I have installed windows through bootcamp to an external ssd, to do that I had to unlock Startup Security utility. It sounds so weird but could this be the reason? Because when I set it to default settings and restart, the temps dropped to 55-60 degree but still seems high right? In any case, I'm planning to return this and re-order a new one with higher ssd capacity so I can install windows directly to Mac's ssd.

edit2: forget what I wrote above, the security is ON now and the temps are the same.