Random shut down on Retina 5K iMac 27-inch late 2014.

I wanted to post the resolution of this to others that might be experiencing a similar problem. My warranty was up soon so I decided to do a fresh install. While I was doing the install, with nothing running, the fan was at full bore and the screen was shutting down. At that point I was convinced it was hardware.

I had one sensor reading that was out of whack; TG Pro calls it LCD Proximity. istat calls it something else; LCD fly lead or something. Anyway I spent an hour with a Genius as he ran all sorts of diagnostics, all of which passed. The diags don't require booting the OS so I was never able to show him the obviously wrong reading (150F where everything else was about 95). So they sent it to a tech and 9 days later they replaced the Display. Apparently the sensor is part of the display and it can't be replaced.

What's astonishing to me was that it took they so long to find it; I would have checked the stray sensor first. Apparently if the diags don't find the problem they just swap stuff out until they find the problem. I guess since the display is the most expensive they do it as a last resort. Kind of odd that they don't have any spare displays in stock (as it was 2 days to get it).

I did a lot of brain picking while I was there and the kernel task thing is definitely the way that the system tries to slow itself down. It seems pretty stupid to me. You'd think in today's world of custom ICs there would be an easy way to just drop the HZ.

So now the fan runs as 1200 all the time and the "LCD Proximity" is steady at 90F; the cpus run at about 90F when idle with the GPU diode the hottest at 100F. Ambient shows 82 and it's about 73 in the room.

Luckily I had another machine that I brought to life so I didn't miss it too much, but 9 days is a long time to do without a computer if it's your only one.

Also note that Apple's full system diagnostic, which took 15 minutes to run, didn't find a faulty sensor. So if you're overheating and you have a sensor out of what makes sense, the in-system diags certainly won't pick it up.

Also, currently the price for a display is $510 plus $79 labor; mine under warranty but it's not a terrible price for a display this good.

I am having the same problem and have to agree. I still respect you as a company, but I would hope that Apple would work to create more sustainable products, rather than flashy ones.

I have been disapointed by my Retina 5K, 27-inch, Late 2014 iMac and I have no desire to ever purchase one of your laptops since you seem to care way too much about how small and unpractical you can make them.

Do not do the same to the iMacs!

and what happened to the macbook PRO??? they're all consumer laptops now. Nothing professional about them.

Hi coke44,

Thanks for using the Apple Support Communities! I'm sorry to hear you are having these issues with your iMac. If you are having intermittent but persistent power or restart issues with your iMac, you may want to try resetting the System Management Controller (SMC) and the NVRAM, as outlined in the following articles:

Resetting the System Management Controller (SMC) on your Mac - Apple Support

How to Reset NVRAM on your Mac - Apple Support

If you continue that have similar issues after a SMC/NVRAM reset, you may need to have your iMac evaluated for service; the following page may be helpful:

Apple - Support - Service Answer Center

Regards

I'm having this same issue. Did you ever figure out what was happening? It's happened to me twice in the last week.

That's great to hear!

I hadn't updated Sierra, instead kept hitting "remind me tomorrow." I'm hoping that was the reason. My iMac and router are plugged into the same outlet and the router hasn't turned off any of the times the mac has, so I'm skeptical about it being the outlet/apartment power.

Mine shuts down regularly. Nothing stops it from happening. The iMac 5K is the biggest piece of junk that Apple has ever produced. I hate it so much can't state it in words.

If there was some way to stop it from shutting down at 90 degrees it would be useful But since Jobs died they have a bunch of morons designing these things.

Just like the dopey cable companies all they can do it tell you to unplug it and wait 15 seconds. How about FIXING THE PROBLEM? they know what the problem is. There's 1000s of these things shutting down all over the world. It's a design flaw. Theres a 2" fan cooling a 5K screen. It's moronic

I've lost confidence in Apple with the iMac 5k. these things are shutting down all over the world, and they can't fit anything. And you have to upgrade the OS ever couple of months only to find that all of the problems remain. They never fix anything. They're just a bunch of greedy geeks.