Random crashes of iMac 27"

[j kev]

I suspect this is not a unique problem. I'm a mathematician who's worked with/on a variety of computers for 40 years, so I think I can recognize a problem. My 27" desktop iMac (purchased new around Christmas 2015) has for the last couple months been crashing randomly. Where by "crashing" I mean it acts like I pulled the power cord.

Crashes are unrelated to my activity. It's even happened overnite when I was logged off. Two Apple help phone calls / interviews yielded nothing. One involved an O/S update (from 13.5 to 13.6): no impact on the problem. The Mac's currently residing behind a local genius bar (and I use that term loosely) for its third day. No report yet. I suspect they're waiting for a crash and will then attempt to, uh, look around for a problem.

I've worked with computers before. As y'all know, intermittent problems are the hardest to deal with, so I appreciate the problem with this problem. But that leaves me with my son's ancient MacBook as a platform in the interim. And access to none of my on-line-purchased apps (like Maple, iBooks [or whatever that bookkeeping s/w is called], Heredis [genealogy], etc.).

So am I gonna have to just sit on my thumbs for a couple weeks until Apple determines that they CAN'T determine the problem and then suggest I buy a new iMac? (Equivalent statement: there goes another USD 4-6K. Bummah.)

 

[mreg376]

1985? Well at least you got a good 33 years out of it...

 

[j kev]

1985? Well at least you got a good 33 years out of it...

Oops. Make that "2015", not "1985". I know I can't type, but I don't think that error was mine. (E-8? I've had a lot of those. E-1985? None I know of...)

 

[cwanja]

Checked any of the logs around the time it crashes?

 

[j kev]

Checked any of the logs around the time it crashes?

I assume the Genius Bar dudettes/dudes will do that. Diagnostics run during one of those phone conversations showed nothing. More info when/if it’s available.

 

[Fishrrman]

What do you mean by "crash"?
Do you get a kernel panic?
Do you get a "freeze" (display on)?
Do you get a "turn off" (computer goes dark, fans stop)?
Or... something else?

 

[j kev]

What do you mean by "crash"?
Do you get a kernel panic?
Do you get a "freeze" (display on)?
Do you get a "turn off" (computer goes dark, fans stop)?
Or... something else?

I mean “crash” in the same sense that just unplugging it would create. No “I didn’t expect that” from the O/S, no display, no fans, nothing. It simply checked out. And when it does, the only recovery is to unplug it, wait 30+ seconds, & plug it in again.
When it reboots it shows the login screen and does NOT report any problems.

 

[Fishrrman]

Next time it does this, reach around and:
1. Press and release the power on button. Anything happen?

If nothing happens with 1 above, next try this:
2. Press and hold the power on button for 6 seconds (count 'em out). Anything happen?
2a. Press and release the power on button again. Anything happen?

It seems like the internal power supply could be "cutting out" -- then perhaps, re-setting itself?

 

[j kev]

Next time it does this, reach around and:
1. Press and release the power on button. Anything happen?

If nothing happens with 1 above, next try this:
2. Press and hold the power on button for 6 seconds (count 'em out). Anything happen?
2a. Press and release the power on button again. Anything happen?

It seems like the internal power supply could be "cutting out" -- then perhaps, re-setting itself?

Tried all that. In each case, nothing happens. When it goes out, it’s gestorben. Kaput. Period.

 

[tubeexperience]

The power supply is faulty and needs to be replaced.

https://www.ifixit.com/Guide/iMac+Intel+27-Inch+Retina+5K+Display+Power+Supply+Replacement/30530

https://www.ebay.com/itm/POWER-SUPP...12-2013-Retina-5K-2014-2015-2017/183023305696

 

[j kev]

The power supply is faulty and needs to be replaced.

https://www.ifixit.com/Guide/iMac+Intel+27-Inch+Retina+5K+Display+Power+Supply+Replacement/30530

https://www.ebay.com/itm/POWER-SUPP...12-2013-Retina-5K-2014-2015-2017/183023305696

Well, hopefully the “geniuses” will figure that out! And (hopefully)^2 doing that will be cheaper than replacing the whole brick.

 

[rick-I]

Well, hopefully the “geniuses” will figure that out! And (hopefully)^2 doing that will be cheaper than replacing the whole brick.

I am a friend of j kev and have been monitoring this thread. What he failed to mentioned is our local genius bar has another identical iMac in for service for the same problem. They already tried replacing the power supply and the problem persists.

 

[j kev]

I am a friend of j kev and have been monitoring this thread. What he failed to mentioned is our local genius bar has another identical iMac in for service for the same problem. They already tried replacing the power supply and the problem persists.

Plus ça change, plus c’est la même chose.

 

[Raven007]

I also had this random shut down problem. Check the computer temperature with Macs Fan Control V1.4.10. iMac will shut down if over temped. First run all fans at 100% for five minutes to blow out all of the accumulated dust. Then set Fans RPM to keep max temp at 150 degrees F.

 

[j kev]

I also had this random shut down problem. Check the computer temperature with Macs Fan Control V1.4.10. iMac will shut down if over temped. First run all fans at 100% for five minutes to blow out all of the accumulated dust. Then set Fans RPM to keep max temp at 150 degrees F.

I’m sure all the Genius worker bees will consider that... but I don’t think there *is* a fan in that Mac. It’s too thin, and I don’t see any vents at all.

 

[Fishrrman]

"but I don’t think there *is* a fan in that Mac. It’s too thin, and I don’t see any vents at all."

The iMacs have fans.

 

[rpmurray]

The OP did mention that it was happening even when logged off and the iMac was idle. Might have to do a Windows and re-install the OS from scratch.

 

[coachtam28]

I suspect this is not a unique problem. I'm a mathematician who's worked with/on a variety of computers for 40 years, so I think I can recognize a problem. My 27" desktop iMac (purchased new around Christmas 2015) has for the last couple months been crashing randomly. Where by "crashing" I mean it acts like I pulled the power cord.

Crashes are unrelated to my activity. It's even happened overnite when I was logged off. Two Apple help phone calls / interviews yielded nothing. One involved an O/S update (from 13.5 to 13.6): no impact on the problem. The Mac's currently residing behind a local genius bar (and I use that term loosely) for its third day. No report yet. I suspect they're waiting for a crash and will then attempt to, uh, look around for a problem.

I've worked with computers before. As y'all know, intermittent problems are the hardest to deal with, so I appreciate the problem with this problem. But that leaves me with my son's ancient MacBook as a platform in the interim. And access to none of my on-line-purchased apps (like Maple, iBooks [or whatever that bookkeeping s/w is called], Heredis [genealogy], etc.).

So am I gonna have to just sit on my thumbs for a couple weeks until Apple determines that they CAN'T determine the problem and then suggest I buy a new iMac? (Equivalent statement: there goes another USD 4-6K. Bummah.)

j kev, is your issue with your 27" IMac resolved? I bought mine around 2015 as well and it started to crashing randomly just like you described about 6 months ago (actually, I think it started a couple years ago and I just didn't realized it because it only crashes when it is in sleep mode and I had to unplug from the outlet before I can restart it again) and Apple Support did everything you mentioned via online help. I took it in to a local genius bar and they ran all the diagnostic tests and can't find the problem and so they reinstall the latest OS and suggest it should fix the problem. Well, it did not so I took it in again a few days ago and now they told me the engineering dept recommends replacing the logic board for $600. I would like to find out how and if you have resolved your problem before I agree to go forward with the replacement of the logic board. Appreciate your feedback. Thanks.

 

[coachtam28]

I am a friend of j kev and have been monitoring this thread. What he failed to mentioned is our local genius bar has another identical iMac in for service for the same problem. They already tried replacing the power supply and the problem persists.

Hi Rick-I, do you know if you friend j Kev resolved his problem with the IMac? I am having the same problem right now and I would like to know how to proceed because the genius bar and their engineering dept is recommending replacing the logic board at $600.