Late 2012 IMac restarts itself

[GMBP]

hi all

I have a min spec 21.5 late 2012 iMac which I received recently.

When I received it was still running Mavericks so I did a factory reset and installed the most recent high sierra upgrade. Since then it has recently started restarting itself without warning, sometimes it does this twice within a few seconds (I know this as I hear the startup noice repeatidly).

It hasn’t actually done this whilst I’ve been using the computer, only when it has been asleep.

The computer has nothing extra installed on it except photoshop and in design cc2018.

Is this a known issue, or is there a known solution? Or is it unavoidable kernel panics which I have done a bit of light reading about?

 

[DeltaMac]

Might be similar to this thread - https://forums.macrumors.com/threads/imac-restarting-itself-automatically-help.1681987/
You might find crash logs in your Console, which may look much like that one in that thread.

What type of internal boot drive/storage do you have?
Hard drive?
Fusion drive?
SSD?

Have you tried booting to Diagnostics (Restart, holding the D key)?

 

[GMBP]

Hi, it has a standard hard drive (1TB).

I realised it may be happening as I assigned Photoshop to use all 8GB of RAM, so I have turned this down to around 4GB and shall await if this helps...

 

[DeltaMac]

The hard drive may be the issue.
Easiest fix for that would be an external SSD, connected through USB 3.0

 

[GMBP]

The hard drive may be the issue.
Easiest fix for that would be an external SSD, connected through USB 3.0

Do you mean to put the OS on an external SSD and use the SSD to boot etc?

 

[Fishrrman]

OP asked:
"Do you mean to put the OS on an external SSD and use the SSD to boot etc?"

Yes.
Setting up an "external boot SSD" is easier than you think.
You won't understand just HOW EASY until you've done it.

Get either a 240gb or 480gb external USB3 SSD -- it doesn't have to be "that large".
256 will do fine, and is very affordable.

Put the OS onto it, along with your applications, and accounts*.
* -- leave the "large libraries" (pictures, music, movies) on the internal HDD. They don't require "speed".

You will have TWO drive icons on your desktop to manage.
But that's EASY.
Again, you won't comprehend how easy it is to manage them until you've done it.