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iMac keeps shutting down randomly

Hi,

I have a late 2015, 27" iMac Retina 5K, running OS X El Capitan Version 10.11.6.

Recently I've been experiencing random, unexpected shut downs. I'm not putting the machine through anything strenuous, just listening to music, web browsing and looking at photos. It shuts off completely with no warnings. The iMac doesn't feel hot.

This has been happening a lot in the last couple of weeks. Although I've noticed the machine has been restarting alot while asleep. When I go to wake it I'm greeted with a message telling me the iMac restarted unexpectedly. To be honest it didn't occur to me that something could be wrong and I ignored it (I thought it could have restarted after updates etc) but the recent complete shut downs have me concerned. When it goes off it won't allow me to turn it back on unless the power cord has been pulled out for a while.

I left it unplugged overnight and removed both external hard drives and USBs. I have been on it most of the day and it's been behaving as normal but just shut down again completely unexpectedly.

I've owned this machine since new and have not had any issues with it unlike my previous late 2009 iMac which gave me continuous grief for 6 years. I have Applecare and spoke to someone on Wednesday about the shutdown issue. She was nice enough on the phone but didn't really help and wouldn't acknowledge the issue even though I was aware this had been happening to other owners, after I did a quick Google search on the issue. I did all the usual resets but still it keeps happening.

She suggested if the problem persisted to upgrade to the latest OS but I'm wary about doing this as I have a lot of third party applications that I'm not sure will be compatible as yet. Also I can't see it being an OS issue as the machine is 2 years old and has been running El Capitan since day 1.

I've read numerous causes from power supply's to poor fan control and overheating but the machine isn't hot, is well ventilated and hasn't been overworked.

Hopefully someone can help. I still have another year of Applecare but I've seen from other owners that unless the shutdown occurs when they are looking/testing it, they won't acknowledge it as an issue. I'm hoping to avoid sending it off at this stage as my previous machine spent more time with Apple repair than it did on my desk.

If anyone knows of a fix I'd be grateful.

Thanks,

Phil

It sounds like your iMac is having kernel panics macOS Sierra: If your Mac restarts and a message appears

It could be software or hardware related, of you can copy and paste a recent panic report it would be helpful.

Also ot may help if you'd download and run EtreCheck https://etrecheck.com/ then post it's result here

Hi Mike,

Many thanks for your reply.

Would a Kernel Panic be the cause of a random shutdown? As I mentioned I was getting unexpected restarts for some time while the machine was idle but now I’m getting complete shutdowns at random intervals. There is nothing new installed or attached to the iMac.

I can’t turn the machine back on unless I’ve pulled the power lead out for a few minutes.

Thanks,

Phil

最後更新：2017-10-16 00:16:48

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