iMac fans don't work after sleep mode

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Level 1

4 points

iMac fans don't work after sleep mode

Hi, I'm having a strange problem with my iMac (Retina 5K, 27-inch, 2020).

After waking up from sleep mode the fans don't work and temps rise until everything becomes unresponsive. I have to shut down and reset SMC to get them working again. After that everything works as it's supposed to until I go to sleep mode.

I'v installed "macs fan control" and it works fine before sleep mode – after waking up it is not responding at all although temp measurement seems to work alright (I can see temps rising but can't change U/min for fans).

At first I thought some temp sensors might be at fault, but "mac fan control" output seems to indicate these work alright. Is there anything else I could try except SMC reset?

Thanks!

Posted on Jul 12, 2021 8:30 AM

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Answer 1

Top-ranking reply

rkaufmann87

Level 10

144,820 points

Jul 12, 2021 8:39 AM in response to stefan_c4

Please reset the SMC 3-4 times with all wired peripherals disconnected such as printer, scanners, cameras,EHD's etc. disconnected. Then retest and add each peripheral 1 by one, test between adding each as you may have a peripheral causing the problem.

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Answer 2

stefan_c4 Author

Level 1

4 points

Jul 13, 2021 1:13 AM in response to stefan_c4

Hi, I've tested your solution and it appears that the samsung t3 ssd is causing the problem. At least in the last 24 hrs fans run even after sleep mode and temps seem to stay low. I've used it for years now and it was always connected – never had a similar problem before. So I guess this is a BigSur problem?!

I'll mark your answer as the correct one and hope this gets fixed …

Thanks!

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Answer 3

rkaufmann87

Level 10

144,820 points

Jul 13, 2021 7:15 AM in response to stefan_c4

The issue is the the Samsung, not Mac OS! This is exactly why I try to steer people away from Samsung and to get OWC drives. Check with Samsung and see if they have more up to date firmware for that model SS.D

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Answer 4

stefan_c4 Author

Level 1

4 points

Jul 13, 2021 7:26 AM in response to rkaufmann87

The SSD worked for years with my older iMac without any problems. It was always plugged in and I never had any problems. Problems started once I updated to Big Sur.

Another thing that happened with Big Sur is that I can't work on files directly from the SSD anymore (i.e. Indesign/Photoshop). But that might be a problem with Adobe software. On the other hand, still works on my old MacBook Pro with up-to-date Adobe CC and always worked on my older iMac before Big Sur.

*edit*

but I will def. check with Samsung reg. firmware

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Answer 5

rkaufmann87

Level 10

144,820 points

Jul 13, 2021 7:39 AM in response to stefan_c4

You don't understand, it is Samsungs (and the user) responsibility to keep their systems up-to-date. This is why Apple has developers programs so developers can work with pre-release versions of Mac OS to ensure their developers have time time to update their stuff to be compatible. Some developers do not keep older systems up to date which is their way of telling you it is time to replace their hardware. We see this all the time with printers and scanners and now some other peripherals.

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Answer 6

rkaufmann87

Level 10

144,820 points

Jul 13, 2021 8:55 AM in response to stefan_c4

It is a collaboration of the developer (in this case Samsung) and the end user. If the end user wants to venture out and use third party peripherals it is up to the developer to keep the product up to date (or not if they want to obsolete it) and it is the developers choice to push the updates to the end user or for the end user to search for the updates.

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Answer 7

stefan_c4 Author

Level 1

4 points

Aug 6, 2021 1:26 AM in response to rkaufmann87

Hi, just a quick update for anyone having this problem (the problem came back after some time even with all devices unplugged).

After some googling I found out that there is a hardware test you can run on startup (press and hold D on intel macs at startup). That test returned error codes and the message that there seems to be a problem with the fans.

Still got warranty so this will be fixed, downside is that it‘ll currently take 1-2 weeks according to the repair shop …

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