iMac keeps shutting down unexpectedly

[Bbguns]

As the title says...
It's a mid-2012 27in i7 iMac. Has been shutting down randomly for a while, getting worse now. Tried SMC and PRAM reset. Clean install of Mavericks. Took it to an Apple Store...couldn't duplicate it there. Have had Apple help chats repeatedly. Allowed them to see the screen and help clean up some files. Have sent them multiple data capture files. They thought it might be the 3rd party RAM (crucial) that I added so I took that out. Still crashed using only factory RAM. Swapped with Crucial, same story. The last few crashes were with Apple RAM only but the engineers reviewing the Data files seemed to think the Crucial RAM was still installed. I've suspected a short or some problem with the logic board...if it can't figure out what kind of RAM is installed, maybe that's the problem. Anyone have any experience with this problem? I searched but haven't seen any recent reports.

Thanks in advance...

 

[boto]

If you happen to experience random shutdowns when your iMac is stressed (games) or it won't restart after testing Apple's Hardware Diagnostics then the issue is the power supply. It took me 2 visits to the Apple store until I could finally replicate it.

 

[Bbguns]

If you happen to experience random shutdowns when your iMac is stressed (games) or it won't restart after testing Apple's Hardware Diagnostics then the issue is the power supply. It took me 2 visits to the Apple store until I could finally replicate it.

It shuts down under low stress...random web surfing, word processing, etc. To restart, SMC reset is required. It used to occur relatively infrequently. Now, I am lucky to get 10 minutes of use. Last shut down occurred during a time machine backup (this normally takes less than 5 minutes). I've seen several threads about this elsewhere and none of the proposed solutions helped. It worries me that some have had logic boards replaced only to see the same thing happen again after a while.

 

[boto]

It shuts down under low stress...random web surfing, word processing, etc. To restart, SMC reset is required. It used to occur relatively infrequently. Now, I am lucky to get 10 minutes of use. Last shut down occurred during a time machine backup (this normally takes less than 5 minutes). I've seen several threads about this elsewhere and none of the proposed solutions helped. It worries me that some have had logic boards replaced only to see the same thing happen again after a while.

Yeah I'm 100% positive it's a power supply issue. The circuits probably got brown and isn't able to remain on. I would suggest visiting the genius bar and have them use their diagnostic test to replicate the random shuts downs as well as proving restarts don't follow through. Mine didn't get as severe as yours but it was progressively getting worse until it became an everyday problem.

 

[garyrh66]

As the title says...
It's a mid-2012 27in i7 iMac. Has been shutting down randomly for a while, getting worse now. Tried SMC and PRAM reset. Clean install of Mavericks. Took it to an Apple Store...couldn't duplicate it there. Have had Apple help chats repeatedly. Allowed them to see the screen and help clean up some files. Have sent them multiple data capture files. They thought it might be the 3rd party RAM (crucial) that I added so I took that out. Still crashed using only factory RAM. Swapped with Crucial, same story. The last few crashes were with Apple RAM only but the engineers reviewing the Data files seemed to think the Crucial RAM was still installed. I've suspected a short or some problem with the logic board...if it can't figure out what kind of RAM is installed, maybe that's the problem. Anyone have any experience with this problem? I searched but haven't seen any recent reports.

Thanks in advance...

You don't happen to use a UPS do you? Because if it is not happening in the Apple store could be a power issue.

 

[Bbguns]

You don't happen to use a UPS do you? Because if it is not happening in the Apple store could be a power issue.

I do use a UPS. But it still crashed when I plugged it into the wall outlet directly. Apple store kept it one night. This was a few months ago when random shutdowns were occurring less frequently.

 

[barbu]

I agree with @boto... Experience would indicate this is a power supply issue. I would (politely, very politely) press for a replacement if you still have a warranty.

 

[Shane1905]

Ah, finally! I've been having the exact same issue with my late 2012 27 i7. I've tried everything to rule out what I can, removing peripherals, swapping out the RAM and it still crashes at random intervals. I doubt it lasts more than a few hours now. It happens no matter what level of demand is placed on it but has passed the hardware test. I recently had it repaired as the hard drive died a week or so before the recal was announced but other than that it's been as solid as a rock. I was going to try wiping it with a clean install to see if that helps, next step apple care again :/

Edit: i also can not just simply turn it back on after it shuts down. I have to unplug the power first and then I can startup, I've had the odd time that it needed to be unplugged a second time to work. Power is getting to it fine so it seems like some kind of self preservation due to whatever the fault is.

 

[Bbguns]

Update:
After 4 months of back and forth with Apple support online...
Tried SMC/PRAM resets, apple hardware testing, disc maintenance, clean install of Mavericks, removal of various programs, manipulation of certain system processes, isolating RAM modules, etc. Sent files to Apple at least 7 times. Then they thought it was a spotlight issue (not sure how...changed OS with clean install, still had shutdowns). Nothing has worked. The interval between shutdowns has narrowed to 20-30 minutes, leaving me with a very large desk ornament. Finally brought it to MacMedics, an authorized repair site. Tech there thinks is hardware, either power supply or logic board, which is consistent with several other threads. I'd suggested this to Apple support several times but they kept following the software processes (which would take up to a week between changes...computer shuts down, e-mailed senior rep who then e-mails 'engineering' who eventually would get back with another option, repeat the process again).
Anyway, I haven't heard back from the repair center yet but I'm hoping they can fix something soon.

 

[ohmyggg]

Anyway, I haven't heard back from the repair center yet but I'm hoping they can fix something soon.

Any update after you brought it into that repair center? Many have reported (on the large thread on the Apple support forums) that power supply and logic board replacements didn't help the issue. I check the threads each day and keep my fingers crossed that some random tech genius figures out that it's a faulty speaker cable causing shortages or something silly like that.

Considering that it's such an expensive machine (out of warranty, in my case) that is unusable, with no solutions from Apple OR the crowd-sourced force of the greater Internet, makes the situation very bleak. Like you said, this thing has become nothing more than a shiny desk ornament.

 

[joelovesapple]

Its the power supply - I had mine replaced on my Late 2012 model. Get it replaced ASAP while it's under warranty.

 

[shaunp]

Take a video of it as evidence and then take it into an Apple store to get fixed.

 

[ennTOXX]

Any update after you brought it into that repair center? Many have reported (on the large thread on the Apple support forums) that power supply and logic board replacements didn't help the issue. I check the threads each day and keep my fingers crossed that some random tech genius figures out that it's a faulty speaker cable causing shortages or something silly like that.

Considering that it's such an expensive machine (out of warranty, in my case) that is unusable, with no solutions from Apple OR the crowd-sourced force of the greater Internet, makes the situation very bleak. Like you said, this thing has become nothing more than a shiny desk ornament.

Have you had any luck? I too had been doing the run around with Apple. Now I'm out of Apple Care and it's been acting up again since I began using it after it sat for several months
[doublepost=1496034709][/doublepost]

Update:
After 4 months of back and forth with Apple support online...
Tried SMC/PRAM resets, apple hardware testing, disc maintenance, clean install of Mavericks, removal of various programs, manipulation of certain system processes, isolating RAM modules, etc. Sent files to Apple at least 7 times. Then they thought it was a spotlight issue (not sure how...changed OS with clean install, still had shutdowns). Nothing has worked. The interval between shutdowns has narrowed to 20-30 minutes, leaving me with a very large desk ornament. Finally brought it to MacMedics, an authorized repair site. Tech there thinks is hardware, either power supply or logic board, which is consistent with several other threads. I'd suggested this to Apple support several times but they kept following the software processes (which would take up to a week between changes...computer shuts down, e-mailed senior rep who then e-mails 'engineering' who eventually would get back with another option, repeat the process again).
Anyway, I haven't heard back from the repair center yet but I'm hoping they can fix something soon.

What did they end up finding and did you get it finally fixed or figured out?
[doublepost=1496034830][/doublepost]

Ah, finally! I've been having the exact same issue with my late 2012 27 i7. I've tried everything to rule out what I can, removing peripherals, swapping out the RAM and it still crashes at random intervals. I doubt it lasts more than a few hours now. It happens no matter what level of demand is placed on it but has passed the hardware test. I recently had it repaired as the hard drive died a week or so before the recal was announced but other than that it's been as solid as a rock. I was going to try wiping it with a clean install to see if that helps, next step apple care again :/

Edit: i also can not just simply turn it back on after it shuts down. I have to unplug the power first and then I can startup, I've had the odd time that it needed to be unplugged a second time to work. Power is getting to it fine so it seems like some kind of self preservation due to whatever the fault is.

I have the exact same issue and I can still hear a light buzzing sound coming from the unit once it shuts off the screen. Apple gave me the run around for weeks and couldn't find anything wrong with the machine. Now I'm out of apple care and after several months on non-use it's back to sitting down frequently when I am using it. With light use mind you as well.

Have you had any luck fixing it?

 

[joelovesapple]

Eventually I found it was the logic board that needed replacing. Fortunately I was within warranty or it would’ve cost a fortune! I’ve since sold the machine (it had had a brand new power supply and logic board so I figured it was like new) and replaced it with the iMac in my sig.

Good luck.

 

[jg39cf]

As the title says...
It's a mid-2012 27in i7 iMac. Has been shutting down randomly for a while, getting worse now. Tried SMC and PRAM reset. Clean install of Mavericks. Took it to an Apple Store...couldn't duplicate it there. Have had Apple help chats repeatedly. Allowed them to see the screen and help clean up some files. Have sent them multiple data capture files. They thought it might be the 3rd party RAM (crucial) that I added so I took that out. Still crashed using only factory RAM. Swapped with Crucial, same story. The last few crashes were with Apple RAM only but the engineers reviewing the Data files seemed to think the Crucial RAM was still installed. I've suspected a short or some problem with the logic board...if it can't figure out what kind of RAM is installed, maybe that's the problem. Anyone have any experience with this problem? I searched but haven't seen any recent reports.

Thanks in advance...

This sudden, random shutting down was happening to me - for years - on my late 2012 iMac. I replaced the power supply and not happened since! (I had taken it to apple 2x, reinstalled the OS, and replaced hard drive previously, none of which fixed the problem. Apple diagnostics always clean.)