iMac gone keeps rebooting itself on start up

Raymond Lin · 21 Aug 2022 at 12:00

I don’t know what’s going on, it was fine on Tuesday but I went away for a few days, came back yesterday and on boot up, about 2 mins after the machine freezes then it reboots.

I’ve tried clearing the vram thing holding down alt cmd r and p, removed the power cable for a bit. It keeps happening.

I can boot into Safe Mode and it’s fine…I’m thinking it could be one of the 3rd party software?

Thoughts?

I tried quitting any apps that tries to open on start up but how do I go into boot up sequence and disable them first?

ChrisD. · 21 Aug 2022 at 12:02

Which model is is specifically?

Raymond Lin · 21 Aug 2022 at 12:06

ChrisD. said:
Which model is is specifically?

Late 2012 Intel i7 on Catalina.

I plan to replace it sometime this year so it’s not the end of the world, photos are on external so a format and reinstall is fine but I rather save that as last resort.

ChrisD. · 21 Aug 2022 at 12:11

Raymond Lin said:
Late 2012 Intel i7 on Catalina.

I plan to replace it sometime this year so it’s not the end of the world, photos are on external so a format and reinstall is fine but I rather save that as last resort.

Might be a hardware fault of some form, try reseating the RAM on it or one stick at a time etc.

Feek · 21 Aug 2022 at 19:53

The Studio is calling you….

visibleman · 22 Aug 2022 at 10:39

Usually i work down this list and test the system after each step; usually one of them will get the system going.

NVRAM reset - https://support.apple.com/en-gb/HT204063
SMC reset - https://support.apple.com/en-us/HT201295
"First Aid" using Disk Utility in Recovery - https://support.apple.com/en-gb/HT210898
Boot into Safe Mode, Uninstall what you think is knackering the system - https://support.apple.com/en-gb/guide/mac-help/mh21245/mac
Last resort, nuke and reinstall.

Feek · 22 Aug 2022 at 11:11

It sounds like the GPU is failing - Do the symptoms match up with this thread, @Raymond Lin?

Raymond Lin · 22 Aug 2022 at 11:37

Feek said:
It sounds like the GPU is failing - Do the symptoms match up with this thread, @Raymond Lin?

I can actually boot into the desktop, all the bits and pieces loads at the top....looks fine, then it freezes...waits a few seconds, it reboots itself.

visibleman said:
Usually i work down this list and test the system after each step; usually one of them will get the system going.

NVRAM reset - https://support.apple.com/en-gb/HT204063
SMC reset - https://support.apple.com/en-us/HT201295
"First Aid" using Disk Utility in Recovery - https://support.apple.com/en-gb/HT210898
Boot into Safe Mode, Uninstall what you think is knackering the system - https://support.apple.com/en-gb/guide/mac-help/mh21245/mac
Last resort, nuke and reinstall.

I am going to go through those, done the NVRAM reset a few times, doesn't work. I can go into safe mode but no idea what is causing it though. Since the machine works for a few minutes before it crashes and reboots. I have time to start closing apps on the top of the task bar to its bare minimum. Thinking it works but then it still crashes.

It's an iMac so I've done the SMC reset by removing the power cable, left it off for like 5mins too.

I am thinking a reinstall is the next step...I mean if I am going to stick it in the corner as a heavy paperweight I might as well try formatting it.

Feek · 22 Aug 2022 at 11:50

Raymond Lin said:
I can actually boot into the desktop, all the bits and pieces loads at the top....looks fine, then it freezes...waits a few seconds, it reboots itself.

It was a known issue on that vintage I seem to remember. My iMac from the same period was subject to a recall for the same thing but I didn't know and missed out.

Hopefully it's not that but it's worth being aware. Good luck with the reinstall if you have to do it.

Raymond Lin · 22 Aug 2022 at 11:56

Feek said:
It was a known issue on that vintage I seem to remember. My iMac from the same period was subject to a recall for the same thing but I didn't know and missed out.

Hopefully it's not that but it's worth being aware. Good luck with the reinstall if you have to do it.

It's not the end of the world, it's coming up to 10 years this Christmas since I bought it so it's paid for itself many times over. Luckily that I wasn't in the middle of editing a set of wedding photos so haven't lost any work and the photos are on external anyway so that is safe.

I can work on my 2018 MBP for the time being with an external monitor and try to fix this but it's a shame i am so close to a full 10 years!

How's the Studio btw, I think I will get the base one and upgrade the RAM to 64G...did you get 1TB SSD?

visibleman · 22 Aug 2022 at 12:02

If it does boot into Safe Mode and doesn't show the same symptom(s), then an app or extension, probably an update, would the logical cause for it. And although you can try and determine which extension by disabling them all and then going through them one-by-one, a reinstall is the simplest solution (especially if data is already backed up) to determine whether or not it's hardware or software - just be wary on app/extension reinstall.

Raymond Lin · 22 Aug 2022 at 12:08

visibleman said:
If it does boot into Safe Mode and doesn't show the same symptom(s), then an app or extension, probably an update, would the logical cause for it. And although you can try and determine which extension by disabling them all and then going through them one-by-one, a reinstall is the simplest solution (especially if data is already backed up) to determine whether or not it's hardware or software - just be wary on app/extension reinstall.

It's fine in safe mode, it's stable there, so it is software, and not hardware....I think?

The easiest solution is to format rather than find the specific piece of software that is causing it.

Feek · 22 Aug 2022 at 12:09

visibleman said:
If it does boot into Safe Mode and doesn't show the same symptom(s), then an app or extension, probably an update, would the logical cause for it. And although you can try and determine which extension by disabling them all and then going through them one-by-one, a reinstall is the simplest solution (especially if data is already backed up) to determine whether or not it's hardware or software - just be wary on app/extension reinstall.

I totally agree with this, if it does run in safe mode for an extended period with a decent load then it's worth trying a rebuild. But if nothing's changed since it was last used then I'd be very surprised if it's a software thing.

Feek · 22 Aug 2022 at 14:07

Raymond Lin said:
How's the Studio btw, I think I will get the base one and upgrade the RAM to 64G...did you get 1TB SSD?

Oops, sorry, I didn't answer this. I went base model Ultra (simply due to an unexpected windfall) and increased the SSD to 2Tb. It took 86 days to be delivered which really dragged. The base Max with 64Gb and a 1Tb SSD is currently showing about seven weeks lead time.

Raymond Lin · 22 Aug 2022 at 14:14

Feek said:
Oops, sorry, I didn't answer this. I went base model Ultra (simply due to an unexpected windfall) and increased the SSD to 2Tb. It took 86 days to be delivered which really dragged. The base Max with 64Gb and a 1Tb SSD is currently showing about seven weeks lead time.

I'll prob go with 512G, but max the RAM as I only put Adobe suite in it and the typical apps, no games.

If it's 7 weeks that makes it mid October....might just bite the bullet this week and do it and use my MBP until then. If i can fix the iMac, great, if not, that's fine too.

Alpherah · 24 Aug 2022 at 11:33

Safe mode is a boot with minimal drivers (and thus minimal hardware) running.
Just because it boots in safe doesn’t rule out a hardware issue.
Could still be a RAM, MLB, GPU issue.

visibleman · 24 Aug 2022 at 12:20

Alpherah said:
Safe mode is a boot with minimal drivers (and thus minimal hardware) running.
Just because it boots in safe doesn’t rule out a hardware issue.
Could still be a RAM, MLB, GPU issue.

Doesn't MacOS still load the (Apple) dext/kexts/sexts for majority of the Apple hardware though in Safe Mode?
I'm probably wrong but i didn't think Apple loaded "generic" dext/kexts/sexts in the same way Windows (or other OS's) does with drivers when they're in Safe Mode (or their variant of it).

But you're right, it doesn't rule out hardware.

Edit - Never really delved into this side of Safe Mode on Apple but a little insight, What does Safe Mode do to an M1 Mac?, Playing Safe: what does Safe mode do?
I would still assume logic board, GPU, drive drivers and extensions to get loaded though....

VaderDSL · 24 Aug 2022 at 12:35

Is anything showing up in the console? Panics etc?

Raymond Lin · 25 Aug 2022 at 18:37

VaderDSL said:
Is anything showing up in the console? Panics etc?

Errr i don’t know what that means…

I did however did a reinstall of Catalina using Recovery Mode. No luck, it still crashes. But doing it this way isn’t a clean install, everything i had is still there. So it’s one of the 3rd party apps.

How do I do a clean install?

Feek · 25 Aug 2022 at 18:43

Raymond Lin said:
So it’s one of the 3rd party apps.

I still think it’s most likely to be hardware.

Alpherah said:
Safe mode is a boot with minimal drivers (and thus minimal hardware) running.
Just because it boots in safe doesn’t rule out a hardware issue.
Could still be a RAM, MLB, GPU issue.

This is what I was alluding to when I said to run it hard for an extended period in safe mode.

When you boot into recovery mode, I believe you can click one of the menu options in the top left and select disk management. From there, I seem to remember you can select to remove the partitions/erase the drive and start from scratch. It’s been a while since I’ve done it.