iMac 5k (Late 2014, 4GHz i7, AMD R9 M295X, Mojave) shutdown/crash.

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iMac 5k (Late 2014, 4GHz i7, AMD R9 M295X, Mojave) shutdown/crash.

My iMac 5k (Late 2014, 4GHz i7, AMD R9 M295X, Mojave) starts to shutdown/crash casually without no visible trace why.

It comes suddenly without any repeatable pre-action, which could show why. It shuts down completely, like an electricity cut.

To start it over, it requires to remove-wait-plug power cable. And then only it starts.

First, it starts, while running a game, so I was thinking it's overheating or corrupted game file.

But now it could happen on a 'cold' mac (GPU 60C, CPU 50C).

Sometimes it's even during the MacOS loading.

After it happens once, it becomes more and more frequent over time. Until it shutdown on load...

The only thing which helps - when it stays shut down for a while. Then you have some time to work...

Here the list what had been already done:

Apple Hardware test (Option+D on boot) - No issues found

RAM test (ramber) - No issues found

GPU Extreme-load ~10min (Unigine Heaven) - No issues (temp 105C)

CPU+GPU Benchmark test (Geekbench 5) - No issues

Re-install of MacOS Mojave from Recovery (CMD+R) - Did not help

Reset of NVRAM (CMD+Option+P+R) - Did not help

I don't know what I can do more - what to test, how to find the issue.

Or, at least, to understand is it software or hardware...

Thanks.

System details:

OS: macOS Mojave 10.14.6 (Build 18G2022)

Model: iMac15,1 (27-inch Retina, Late 2014)

CPU: Intel Core i7-4790K @ 4.00 GHz

RAM: 32GB 1066 MHz DDR3

GPU: AMD Radeon R9 M295X 4GB

iMac with Retina 5K display, macOS 10.14

Posted on Jan 12, 2020 3:30 PM

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Answer 1

Best reply

den.thed

Level 9

77,488 points

Jan 12, 2020 4:04 PM in response to n01known

Startup in Safe Mode and see if it still crashes and/or shuts down.

see > Use safe mode to isolate issues with your Mac - Apple Support

If it doesn't crash and/or shut down, then it could be cause by some third party process or hack.

If it does in safe mode, then you need to make an appointment and have the Apple Tech run his Diagnostic Test on it.

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Answer 2

n01known Author

Level 1

5 points

Feb 15, 2020 12:27 PM in response to W. Raider

So, in my case, the problem was with power supply unit.

The easiest test is to check kernel shutdown return code. If the number is positive, then it's a software problem; negative - hardware (e.g. temp). If zero - power cut-off.

Here is the command to check shutdown code:

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

Here is some useful links:

https://georgegarside.com/blog/macos/shutdown-causes/

I just bougt a new PSU unit on ebay and replace it myself. As bonus I've upgrade hdd to ssd, too.

[Link Edited by Moderator]

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Answer 3

den.thed

Level 9

77,488 points

Jan 14, 2020 5:47 PM in response to n01known

It's impossible to tell for sure if it software or hardware related at this point. From your description, it kind of sounds like some process is failing or running a-muck and causing it to overheat or crash, but that's just a guess at this point.

Please run EtreCheck Pro and post back here with the Report.

see > https://apps.apple.com/us/app/etrecheck/id1423715984?mt=12

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Answer 4

W. Raider

Level 3

784 points

Feb 13, 2020 2:36 PM in response to BDAqua

I've been using SMC Fan Control for years and years and I have pre-sets in it for when I'm editing or exporting/encoding video.

Macs Fan Control WHILE I'm editing some 2K video in Final Cut Pro when the fans were at ≈ maybe 2300-ish

I've seen the GPU diode get to 214°F.

Also I've noticed in Activity Monitor that the GPU seems maxed out in GPU History while I edit lately.

AMD Radeon R9 M295X

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Answer 5

n01known Author

Level 1

5 points

Jan 14, 2020 4:13 PM in response to den.thed

Unfortunately, after error had happen, it's failing during the loading screen, and not load into Safe Mode.

After some 'cooldown' period (~5min) it's loading into Safe Mode, but I could not replicate the error.

I'm going through the log in Console, but nothing too obvious there.

One more detail - a volume button disappears from menu bar and needs to be readable from System Preferences.

Apple Tech is the last option. Before that, I would like to make sure that I've done what I could.

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Answer 6

W. Raider

Level 3

784 points

Feb 13, 2020 12:01 PM in response to n01known

I have a similar problem on the same model iMac. The iMac shuts down during exporting from Final Cut Pro X and Compressor.

The way it shuts down is a bit odd; suddenly the screen will go black, iTunes will stop streaming music and then all my external HDs will spin down. Then they'll spin back up and the iMac will actually shut down. I can immediately tap the power button and boot back up. It seems to only happen during video exports from Compressor and I think FCPX.

Things I've tried:

I've stress tested the CPU (8 cores I think) for a while by sending "yes" to dev/null for a good 10mins and the fans kick in and and it gets hotter but won't shut down.

I've toggled various settings in FCPX and Compressor changing the instances of Compressor and using the GPU for encoding.

I've reset the SMC and the NVRAM.

I've blown dust out of the iMac as best I can without taking it apart.

Just today I tried to make it happen to show someone and couldn't so it's one of those frustrating problems that's hard to reproduce for me. I do notice that the GPU is used heavily when editing in FCPX and when Exporting video.

I was trying to get it to happen so I could run log show to show events related to shutdowns (searching reveals nothing so this shut down is quite abrupt, leading me to think there's no time to write anything to a log file)

I'm beginning to suspect it's a power supply issue now or possibly something going wrong with the heatsink. I just don't want the hassle of ungluing the iMac to get inside and then deal with gluing it all together again.

From what I've read elsewhere Apple Techs will run a stress test overnight and typically not find anything. It's not uncommon to come across this sudden shut down issue with iMacs from this time period.

If it happens again run this in the Terminal (it'll take a little bit to produce results so be patient)

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

If you want an simple way to stress test the CPUs run this in the terminal

yes > /dev/null &

once for each core you have, so for eight cores it would be:

yes > /dev/null & yes > /dev/null & yes > /dev/null & yes > /dev/null & yes > /dev/null & yes > /dev/null & yes > /dev/null & yes > /dev/null &

IMPORTANT!

To stop yes going to dev/null run this in the Terminal:

killall yes

The one thing I haven't tried yet is booting to safe mode and messing around. I may do that this weekend.

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Answer 7

BDAqua

Level 10

239,615 points

Feb 13, 2020 2:17 PM in response to W. Raider

What temperatures does this App report?

This App can be used to speed up the fans, all my iMacs would be dead without it.

Never ever ever drop fan speeds below the speed that the Mac itself is calling for.

MacFansControl…

https://www.crystalidea.com/macs-fan-control

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Answer 8

W. Raider

Level 3

784 points

Feb 13, 2020 3:29 PM in response to BDAqua

I've never seen at least the CPU Proximity temp get above around 151°F, maybe a tough higher. When the shut downs occur i'm transcoding video (exporting) and the CPU Proximity temp is around 150F but when I export things tonight and tomorrow I'll keep an eye on what Macs Fan Control is reporting and report back here for sure.

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Answer 9

n01known Author

Level 1

5 points

Jan 12, 2020 3:34 PM in response to n01known

Oh, and I've run Disk Utility - First Aid on a hard drive - No issues found.

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Answer 10

W. Raider

Level 3

784 points

Feb 13, 2020 12:47 PM in response to W. Raider

I just realized booting into Safe Mode isn't an option for me since Safe Mode doesn't support OpenGL hardware acceleration, I think, so Final Cut Pro X won't launch in Safe Mode.

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