IMac shutting down randomly

[Richsilver]

My late 2012 iMac 27" is shutting down randomly. It's been getting more frequent now shutting down 6 or more times in a day. In order to re-start I have to reset the SMC every time by unplugging the computer.

I thought it may be an overheating problem, so I installed iStat to monitor the temperature sensors. Looking back at the history, all appears to be normal right before a shutdown.

Any help would be appreciated.

 

[honestone]

Need to ask some questions:

1. What exact Mac OS are you using?

2. Have you ever done an disk cleanup/maintenance/repairs, from a software perspective? By that I mean have you ever run any disk-related software to help with those tasks? There are some excellent products available (both free and commercial) that can help you with that.

3. This is critical: are you making backups to an external device? If yo are, what software are you using for that?

4. How are you making posts here? If it's another Mac, what exact model is it, and what exact Mac OS are you using on that machine?

Once you answer those questions, we can better assist you.

 

[Richsilver]

Thanks honestone for your offer to help, but I'm virtually certain my problem is a hardware one and could not possibly have any relevance to backups, disk cleanup or the computer from which I am posting.

 

[honestone]

It is possible to remedy the issue with some software. But if you don't want my help, fine.

 

[Cory Cooper]

Actually, this is a semi-known hardware issue, normally related to a failing power supply. Some models had similar issues related to the graphics card, but more often it is a thermal issue in the power supply.

-What is the exact model of iMac?
-Have you run this: How to use Apple Hardware Test on your Mac

It may be best to take it to an Apple Store for full hardware diagnostics, if that is possible.

C