Imac 2020 locks up then reboots

[normski4ash]

I have a new imac retina 5K, 27" 2020, 3.6GHz 10 core intel i9, 8 GB DDR4 ram, AMD 5500 XT 8GB Graphics.
Been OK since I bought it 6 weeks ago, now I come to it some days and several strange things are happening.
First thing I notice is left clicking the mouse or trackpad on say a folder on desktop and nothing happens, double left click and the folder opens. Second thing is I went to Google to try and ask the question, only the keyboard doesn't work either. (should say all new magic keyboard, mouse and trackpad with the inbuilt lithium batteries) Cannot type anything.
Dug out an old usb keyboard, plugged in and it works fine.
So I thought let's try a reboot... Click the apple, top left, nothing, double click the apple, nothing... Can't even reboot.
OK only one thing to do is hard shut down, press on/off button for 6 seconds until it dies.
Give it a minute, press on button, wait until it loads... Message, "you shut down you're computer because of a problem (or words to that effect) Yes, send report to apple...
This has happened 3 or 4 times over the last week, today it did it again, then it turned itself off... BANG, black screen... musing about it and it booted itself back up again... sent the report to apple and we are working again.
Initial thought is that I have installed a couple of crucial 32GB DDR4 memory modules, thus giving me 72GB with the pre installed 8GB. So have just powered down, removed the two 32's and trying that for a while see what happens. Though I have to say that I installed these the day it arrived and has been working fine up until now !
Suppose next step would be to un install my apps, one at a time to see if there is a conflict with one of those, but the new imac is a mirror of my old 2012 27" imac, and that has no problems with all the software that is on it...
Any thoughts/ideas/advice gratefully received...
Thnx in advance, Normski

 

[anthony13]

I have a new imac retina 5K, 27" 2020, 3.6GHz 10 core intel i9, 8 GB DDR4 ram, AMD 5500 XT 8GB Graphics.
Been OK since I bought it 6 weeks ago, now I come to it some days and several strange things are happening.
First thing I notice is left clicking the mouse or trackpad on say a folder on desktop and nothing happens, double left click and the folder opens. Second thing is I went to Google to try and ask the question, only the keyboard doesn't work either. (should say all new magic keyboard, mouse and trackpad with the inbuilt lithium batteries) Cannot type anything.
Dug out an old usb keyboard, plugged in and it works fine.
So I thought let's try a reboot... Click the apple, top left, nothing, double click the apple, nothing... Can't even reboot.
OK only one thing to do is hard shut down, press on/off button for 6 seconds until it dies.
Give it a minute, press on button, wait until it loads... Message, "you shut down you're computer because of a problem (or words to that effect) Yes, send report to apple...
This has happened 3 or 4 times over the last week, today it did it again, then it turned itself off... BANG, black screen... musing about it and it booted itself back up again... sent the report to apple and we are working again.
Initial thought is that I have installed a couple of crucial 32GB DDR4 memory modules, thus giving me 72GB with the pre installed 8GB. So have just powered down, removed the two 32's and trying that for a while see what happens. Though I have to say that I installed these the day it arrived and has been working fine up until now !
Suppose next step would be to un install my apps, one at a time to see if there is a conflict with one of those, but the new imac is a mirror of my old 2012 27" imac, and that has no problems with all the software that is on it...
Any thoughts/ideas/advice gratefully received...
Thnx in advance, Normski

Not sure what is causing your problem, but as for the RAM, I would remove the two stock apple RAM sticks and just use your crucial ram (put those in the same slots your apple ram was). Using different capacity chips is reducing your ram speed.

 

[normski4ash]

Not sure what is causing your problem, but as for the RAM, I would remove the two stock apple RAM sticks and just use your crucial ram (put those in the same slots your apple ram was). Using different capacity chips is reducing your ram speed.

 

[normski4ash]

Oh right, thanks, didn’t know that. Not the crucial ram though ‘cos it’s done it again with just the apple ram. Will remove the apple and replace with the crucial tomorrow.

 

[pmiles]

Have you tried a NVRAM or PRAM reset?

Reset NVRAM on your Mac - Apple Support

If one or more settings stored in NVRAM don't work as expected on an Intel-based Mac, resetting NVRAM might help.

support.apple.com

Try reinstalling the system OS? This won't erase the content on your drive, just reinstall the OS unless you tell it t erase the drive.

How to reinstall macOS - Apple Support

You can use macOS Recovery, your computer's built-in recovery system, to reinstall the Mac operating system. Reinstalling macOS doesn't remove your personal data.

support.apple.com

 

[normski4ash]

Have you tried a NVRAM or PRAM reset?

Reset NVRAM on your Mac - Apple Support

If one or more settings stored in NVRAM don't work as expected on an Intel-based Mac, resetting NVRAM might help.

support.apple.com

Try reinstalling the system OS? This won't erase the content on your drive, just reinstall the OS unless you tell it t erase the drive.

How to reinstall macOS - Apple Support

You can use macOS Recovery, your computer's built-in recovery system, to reinstall the Mac operating system. Reinstalling macOS doesn't remove your personal data.

support.apple.com

OK will give it a go tomorrow. Not fussed if totally wipe drive, all photos, music, videos etc live on external drives, so just a case of re installing programs. Actually might just re install Photoshop suite and leave it at that. Can do everything else on older iMac. Cheers

 

[normski4ash]

OK so reinstalled Catalina on Wednesday, it is now Saturday early afternoon, and so far, touch wood, it hasn't locked up on me... Fingers crossed X.
Had a web chat with apple, told them what you suggested and they said that would have been there first advice (yeah yeah)...

 

[mark why]

I have almost exact same problem with 10-core iMac. Once every few days it just goes blank and the reboots itself. Sometimes it happens twice in a row, then not again for a few days. After several calls to Apple support, they are still saying they don't have any reports of this problem. They had me try SMC reset, but that didn't work. If you take it in for repair, you may have to leave it there for a few days until they can replicate and analyze the problem. Since the 10-core iMac is now quoting mid-December (6 week) delivery, it may take a long time to get a replacement logic board if needed. It's a big problem if you can't do without your computer for several weeks.

By the way, mine was all-Apple, no third party add ons.

 

[normski4ash]

I have almost exact same problem with 10-core iMac. Once every few days it just goes blank and the reboots itself. Sometimes it happens twice in a row, then not again for a few days. After several calls to Apple support, they are still saying they don't have any reports of this problem. They had me try SMC reset, but that didn't work. If you take it in for repair, you may have to leave it there for a few days until they can replicate and analyze the problem. Since the 10-core iMac is now quoting mid-December (6 week) delivery, it may take a long time to get a replacement logic board if needed. It's a big problem if you can't do without your computer for several weeks.

By the way, mine was all-Apple, no third party add ons.

My first thought was the memory son took it out, but it still did it, so replaced the crucial memory. After reinstalling the os it hasn't done it, could be worth a go, it's dead simple.