iMac (Retina 5K, 27-inch, Late 2015) Randomly Restarts Without Errors

Came back after a week away or so, and the unthinkable has happened - more cut outs. (*My issue went straight to black - no restarts) Unplugged a couple of times last night and had to give up. Happened as soon as I logged in (still on Yosemite 10.10.5) though wouldn't make a difference if I upgraded to El Capitan I'm sure. Problem only occurred after updating to 10.11.5. (That blasted minor update!!!!!!! ⚠)

I'm assuming now that I'm also in line for a Logic Board Replacement - though at my own expense, as I only THOUGHT I had bought AppleCare. This morning though, turned on and about after an hour or so, turns off again. Waited a few mins. Turns back on and currently typing this. Still haven't found a permanent solution (I reinstalled through Internet Recovery Mode, Yosemite, after wiping the iMac). Seems strange that a minor software update can render a $3.5K iMac completely useless. Really unhappy about this.

Things have changed in the last day. Before the iMac would reboot itself when it got into this state, but now the screen just goes black and I have to recycle the power manually to bring it back up.

Which would seem to point more and more at a sleep related issue. Clearly here the machine had gone into sleep mode and simply could not rewake from it cleanly.

Trying to post the results of the test. Just getting "invalid characters" notice and times out. Any thoughts?

All the best,

Reynolds Young

Arlington VA

I assume you're talking about the Linc Davis script? In his instructions for running the script, towards the end, he offers a solution to this problem: post the script on pastebin.com (you can set it to expire after x amount of time if you're worried about it staying online forever) and then bring the link here.

-Jon

Thanks so much, Jon...I have a habit of missing the details. You pulled me out of this one!

Have a VERY good 4th!

Reynolds

Now, copied to Pastebin...all is well.

Reynolds Young

Arlington VA

One week now with new logic board and 10.11.5: NO RESTARTS! Cautiously optimistic that it's fixed. All the trouble started with the 10.11.4 update, not the 10.11.5. For what it's worth, my Mac Air (late 2010) has 10.11.4 and has never had any issues.

wyowoman, big thank you for the update––must be that Wyoming (you're in Wyoming, right?) hospitality! Your neighbors to the south in Colorado appreciate it!

It is July 4th, so obviously big holiday here in America––I'm hoping to hear back from the engineers, possibly about getting a replacement video card or logic board, tomorrow. Since I reinstalled the Apple RAM and took out my CDW RAM the computer has continued to restart randomly and I've documented every instance of it with Console logs. I'm ready for this issue to go away entirely.

This is interesting, I've got a Mid-2015 5k iMac (15,1) which keeps turning off (no restart) and it's been happening since April. I took it to my local Apple store and they insisted it was software and kindly uninstalled Adobe Creative Cloud.

Needless to say, it didn't solve the issue, and sometimes the power failures wouldn't even let me get through the both sequence they happened so frequently.

I'm convinced it's power or heat related (keep reading). At first I was worried that it might be a power quality issue, but there aren't any signs and symptoms of anything else being affected.

I've been busy for the last few months and I found a way to "manage" the issue.

I found that if I shut the computer down at night and LEFT IT UNPLUGGED (that bit is important), it would work fine for as long as I needed it the following day. If I forget to unplug it, I get hardly any use. The longer it has been plugged in, the more likely it is to turn off.

I've recently come back from holiday and I thought this problem had magically gone away. I've had almost 20 days uninterrupted use with no problems and I haven't shut the computer down once.

Tonight it happened again.

Tomorrow is 1 year since I purchased it.

(As a final kick from Apple while I'm down, I just tried to hurriedly purchase AppleCare and the website is just displaying a blank page.)

Yup, I am here in small town Wyoming. Not sure why the apple service place was so quick to replace the logic board on only my second visit (after the memory fix failed) but it seems to have done the trick. I was armed with all kinds of evidence from this discussion about others who got logic board fixes from Apple stores but it turned out I didn't have to make the case. I think there was some communication between Apple and the service place but I can't be sure. Keep on pushing because it seems to have worked for me and others.

FWIW, and I'm not a tech expert, but the fact that unplugging the computer seems to help the situation indicates perhaps that it's an SMC issue; on iMacs, SMC is reset by unplugging the cord from the computer.

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

I'm having same issue on my brand new iMac purchased roughly 2.5 weeks ago. I'm extremely disappointed with Apple. After encountering logic board issues on my 2010 MacBook Pro (I had to pay to have the logic board replaced initially, then I was reimbursed when apple admitted fault in hardware), and now encountering this random restart, in the middle of my workflows nonetheless, I'm angry and don't want to shell out any more money on Apple products. We miss you Steve!

From this forum it seems to be a logic board issue but I cannot get Apple to approve the replacement of it in my machine. They want me to leave it for a week or two to run tests - I feel this is unnecessary and a big inconvenience for me. If they read this thread those who have left it for a two week period were given their machines back saying all is well and the random restarts continued.

Random Restarts with no error message in all cases here - how are they going to pinpoint the issue if there is no Error in the log? I have two exact restart times to send to Apple today in the Logs - both with no error messages. It just freezes and restarts.

Will N-E-V-E-R buy another Apple product - phone, tablet, watch, car - N-A-D-A. Customer service is by far the worst of the worst. All read you the same 3 x 5 card - "If I were you I would be extremely frustrated too." Well you are not me and your false sympathy just ****** me off more. Done.