iMac Random Shutdowns

I too read it as a (deserved) dig about “tech savvy”, not one against teachers.

But then my father is considered tech saavy because he knows how to use iPhoto (but is utterly confused about using iTunes to sync pictures to his iPad).

It’s all relative.
To the confused teacher that other teacher was “tech savvy”.
He probably knows mare than the other teacher does about computers and has helped them a few times.
So he’s the go to guy.
To many of us he might seem not tech savvy at all.

This is getting WAY off topic

Uh oh. Stroke a nerve again :s Ouch…

Now that you mention it, they were not teachers at all. It never happened. It was a weather balloon. Teachers are absolutely perfect in every way. There :stuck_out_tongue:

Looks like a power issue. But it also seems the problem may be more common, and seems to happen with many models :
https://duckduckgo.com/?q=imac+shuts+down+on+itself

Most conspicuously, https://discussions.apple.com/thread/3867688?start=15&tstart=0 long thread on Apple forums which is about 2012 27" iMacs…

Hypothesis run from overheating to defective power supply…

I have yet another idea : could it be that the power in your house had some irregularities ? Not enough to be a problem for regular appliances, but sufficient to turn off your machine. I remember experiencing strange power spikes in California. As we all know, transformers may not always be as reliable as one hopes in certain areas.

The sure way to check would be to put it on an uninterruptible power supply and see if it still manifests. Another if you have a voltmeter handy, plug it in on the same outlet and when the Mac goes down, take a reading. I have seen sometimes power go down to 100 volts or even less.

It is “possible” that I’m experience minor “brownouts”… but I think highly unlikely… for a number of reasons. One, SDG&E (San Diego Gas & Electric) is a very stable supplier, and they usually give a few hours notice if brownout need to happen … so that computers etc can be dealt with safely. Plus I have 4 other computers that don’t seem to be affected (although they are all plugged into other outlets, but may share the same master circuit). I would think if it were the power supply (and it might be), that it would be more consistent than it has been.

It was shutting down every 2 to 3 hours until I changed the power strip for a new one, then it ran for like 8 or 10 hours, and crashed twice in an hour, but has now been running for 15 hours without a problem

[quote=210485:@Dave S]It is “possible” that I’m experience minor “brownouts”… but I think highly unlikely… for a number of reasons. One, SDG&E (San Diego Gas & Electric) is a very stable supplier, and they usually give a few hours notice if brownout need to happen … so that computers etc can be dealt with safely. Plus I have 4 other computers that don’t seem to be affected (although they are all plugged into other outlets, but may share the same master circuit). I would think if it were the power supply (and it might be), that it would be more consistent than it has been.

It was shutting down every 2 to 3 hours until I changed the power strip for a new one, then it ran for like 8 or 10 hours, and crashed twice in an hour, but has now been running for 15 hours without a problem[/quote]

If it is not a brownout, it sure looks like a failing power supply. On the grid or within the machine. Whichever it is, I find it kind of suspicious that dozens of users seem affected besides you. To me, that looks terribly much like some kind of issue with the 2012 27" iMac. May not be with every one of them, could be a batch, but it does not seem to be a whimsical rare occurrence. I would bet the power supply is simply a tad peculiar about voltage level.

Fact is you need to corner that gremlin one way of another…

We had a similar problem recently in our office with random shutdowns. Turns out the UPS was failing, not the computer (which happened to be a Windows machine).

Being in Phoenix, one of my first thoughts goes to central air conditioning or a failing refrigerator compressor sucking too much power and dropping the voltage just enough to cause the iMac to shutdown.

If they’re laptops, they don’t count, as they have batteries. Is the iMac on the same circuit as the fridge?

[quote=210485:@Dave S]It was shutting down every 2 to 3 hours until I changed the power strip for a new one, then it ran for like 8 or 10 hours, and crashed twice in an hour, but has now been running for 15 hours without a problem
[/quote]
That also sounds like it could even be a bad outlet… loose screw?

I also didn’t see anyone mention testing your RAM… MemTest86.

Be nice to dave :slight_smile:

Did Jim say he thinks I have “a screw loose”? LOL

Well at 1:32 in the early morning, it shut down again (according to the console logs), and I HAD noticed that while I replaced the main power protector, the computer was actually plugged into a strip that was plugged into THAT strip… No longer, the computer now goes DIRECTLY to the main power.

$45.00 seems rather excessive for a memory test… I will see with the built in Apple Diagnostics tell me first :slight_smile:

[quote=210650:@Dave S]$45.00 seems rather excessive for a memory test… I will see with the built in Apple Diagnostics tell me first :slight_smile:

[/quote]
There’s a free version on that page too , you can make a bootable USB stick or CD with the ISO image. The $45 version basically has a few extra options

No comment :wink:

I just ran the built in Apple Hardware Test (AHT), took 1/2 hour and reported no troubles. will see if I can find that “free version”

Just below where it says “MemTest86 V6.1.0 Free Edition” there are links for linux/mac ISO’s

For those interested… after three months, and 3 trips to the “genius bar”, and countless phone calls and emails with an Apple Care rep, they replaced both the logic board and the power supply… but in the process removed 1/2 the memory… Memory that came with the machine when purchased from Apple, not 3rd party after the fact.

So, now I have more phones calls pending (the store and AppleCare), and get to look forward to disassembling the whole setup for the 3rd time and transporting it back, and expect nothing more than a “oops” from them