iMac Pro restarts every day or so

My iMac Pro restarts almost every day. It started when I upgraded to Big Sur (I think) but it is still the case after a downgraded to Catalina it still happens every night.

It only restarted when it was locked, so maybe a energy saving issue or hardware fault? I honestly have no clue.

If it were just me, this would be just a nuisance, but my spouse needs to run some multi-day calculations :frowning:

I appreciate hints and tips.
I searched, but only found boot loop problems, which I don’t have.


Edit: it also restarts when no calculations are running.

I had this with my MacBook. I couldn’t find a solution so as a last resort I did a nuke and pave (I reinstalled Big Sur). Since that it’s never happened again.

I am under the impression that Big Sur upgrades the firmware on your machine, and there is no way to go back to Catalina’s firmware. Therefore your firmware and your kernel are incompatible.

I suggest that you go back to Big Sur. As @Rob_Polding said, it may be necessary to perform a nuke and pave to get this to work correctly.

Hm, I did nuke and pave to install Catalina.
Assuming I can create an USB installer for Big Sur I will try that tonight.

If the firmware was upgraded, it makes a bit more sense, why going back to Catalina did not help.

Will try and report back. Thank you!
If you don’t hear from me for a week, assume it is still running … fingers crossed.

My MBP did that every 3-4 days when it was on Mojave. Moving to Catalina fixed it. It don’t think it was Catalina that fixed it, it was just that the macOS reinstall fixed some bug.

There’s the old “reset the (smc, nvram, pram)” voodoo

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Thank you all!
I did reset NVRAM just to be on the safe side, and did a fresh install of Big Sur.
Until now, I had no restarts :slight_smile:

When I upgraded to Big Sur, Sidecar and Unlock with Watch did not work, and now they do! Probably due to resetting the NVRAM, but it feels so much better, when everything works as expected.

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Glad you got it sorted.
Nothing like a $5k computer that does weird things.

Haha, yes, I had thoughts along those lines.
Too much money for a brick.

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