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2019 iMac Randomly shutting down and won't start

J

Jong875

macrumors member
Original poster
Feb 5, 2015
83
21
My iMac shuts down randomly recently. Sometimes while I'm on it and sometimes while its in sleep and I can't turn it back on unless I unplug it or sometimes hold the power button down for awhile. It just becomes unresponsive. Anyone have this issue?

I9 512Gb SSD.
 
I had this issue with my 2013 iMac. It started turning off randomly at the end of 2017 and only happened once every couple of weeks. It progressively got worse over months to the point it shuts off daily. I tried the PRAM reset and even reinstalling the OS, but it continued. I bought a new grounded power strip and that didn’t help. I was fed up so I got Apple involved. Apple Engineer’s spent hours trying to troubleshoot remotely and found nothing. They checked my log files, and even when the iMac shut off in the middle of the test, it showed NOTHING. They booted into safe mode, and it still randomly shut off. Because of this, they suggested it was probably defective hardware. I brought it into the Apple store 3 times. The first time they replaced the RAM and said it passed their diagnostic test. I brought it home and it continued to happen. I went back to the store and they changed the battery supply and it passed their diagnostics. But it continued to happen at home. The final time I brought it in they replaced the logic board and the issue seemed to be resolved. However, they put the wrong board in my iMac so they ended up giving me a new one, so I am not completely sure. The new iMac Has had no issue for the past 6 months I’ve had it. As someone who has troubleshooted a lot of tech issues on my own, this experience was BY FAR the most frustrating I’ve experienced. I honestly couldn’t believe that Apple’s own Engineer’s had no viable diagnostics to identify the problem, hardware or software. Something was obviously failing. And by the way, I paid out of pocket for each repair. At the time, I searched for solutions online and found people going through similar situations with random shut downs, and Apple wasn’t able to diagnose the problem. If your situation is hardware related, it seems different replacements work for different people, so it could be a process of trial and error. I can only hope it’s as simple as a PRAM reset for you. Good luck!
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I forgot to include that the symptoms were the same as yours. When it shut down randomly, I needed to unplug it for a few seconds or else it wouldn’t power back on.
 
Jong875 said:
My iMac shuts down randomly recently. Sometimes while I'm on it and sometimes while its in sleep and I can't turn it back on unless I unplug it or sometimes hold the power button down for awhile. It just becomes unresponsive. Anyone have this issue?

I9 512Gb SSD.
Click to expand...
I had the same exact problem as you with the same 2019 iMac configuration (i9, 512Gb SSD and Vega 48). Finally it even did not to turn on at all. I returned the computer and they told me that it was a manufacturing problem. They gave me back my money.

What GPU has your iMac, the 580X or the Vega 48?

Now, I am about to order a new i9 with the 580X instead of the Vega 48, but the previous seller did not tell me what exactly was the factory problem with the returned i9 iMac (logic board, GPU, CPU, PSU, RAM, etc.). I think that these cases of iMac i9 random failures are more common than they want us to know due to thermal constrains. But I can not confirm this fact with so little evidence as the few cases in this forum. Of course, an Apple expert for business sector told me recently that there are no problems with this i9 confinguration in the iMac, unlike the MBP i9 of 2018, but lets give them some time.
 
I have the 580x

I did the remove the power cord and hold the power button down for a few seconds and it seemed to help for now.
 
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Jong875 said:
I have the 580x

I did the remove the power cord and hold the power button down for a few seconds and it seemed to help for now.
Click to expand...
I also did that, but the computer was already dead, not turning on at all. I also contacted with Apple Tech Support team and they confirmed that there was a hardware manufacturing problem (probably logic board overheating). The problem with the 2019 iMac is that, as the GPUs are integrated in the logic board, if they overheats, this could damage the logic board. One single fan for the CPU and for the GPU could not be enough for dissipating the extra heat. For people living in hot regions this is a big problem for the computer long term reliability and performance.
 
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