Why is my imac shutting down by itself?

Not the Seagate drive.

System lasted about three hours then shut off when I was using Mail (which is a common occurrence, as well as Safari and Photos). I'm not sure I noticed this because it happens specifically when I use these programs, or because I use these programs a lot compared to others.

Back to the drawing board. Oh, back in March, I did follow the procedure for getting the code for the shut down - I don't remember the exact code, but it was the "could be anything" code - no help there.

I can not find SystemConfiguration in the Preferences folder.

Please advise.

Hi all. I'm really just chiming in here obviously for anybody in recent history that's been searching for a solution on this unprovoked shutdown thing. My opinion, in my case - and I feel kind of stupid about it - is that it is indeed about heat. I've had numerous iMacs over the years, and the most recent is a mega slim, late 2012 27", w/2.9 i5. This machine, not long ago started to just...black out. Gone. Sometimes it could be restarted immediately. Sometimes it required pulling the power cord (which made me think the reset was telling me the power supply was going, which I've had before). I'd tried PRAM and other magic, but no real organized plan. And it was always after I'd been working on it for a while, never just a short stop (I also use a MBP extensively, and am not often home to do heavy lifting on the big screen).

Today, it went down; I unplugged briefly, started up. Then it happened again, just minutes later. It's a warm day here, but not so warm that I have AC on, so it's actually a little hotter than usual upstairs where this machine is, with the window open. So at this point, no startup, no matter what. Let it sit for a minute or two, no go. No chime, no nothing.

I then pondered previous machines and the dust I'd found in them when I'd cracked them open for some reason, and I simply flipped the thing upside down and started blowing in the whole row of vents on the bottom edge. And yeah, the dust started flying out. I didn't even bother with compressed air or anything, this felt like my answer, and I'm pretty sure it was, as it started immediately, and hasn't shut down since. I suppose in the interest of full disclosure, I'd also unseated and reseated the RAM while I had the thing flipped over, but it really feels like dust and heat to me.

Not saying this is 'the solution' for even a large percentage of you folks, but I'm here to remind you of the potentially obvious solution...that I had obviously forgotten!

Thanks for your response.

I haven't completely ruled out heat, although my numbers seem to fall within everyone else posted norms. I suspect that after today it may be GPU cooling, as it went through a spasm of random screen draws resulting in a colorful collage of bits and pieces of my open windows before it went down.

When it first started doing this back in March, the first thing I did was clean out the dust and yeah, I reseated the RAM as well. I might have to crack this baby open and give it a thorough cleaning. Been meaning to anyway.

Yep...I had a similar spasm on my previous iMac, followed by the [unbelievably slow everything/beachball all the time] bit, which felt an awful lot like a bad power supply. That one is still sitting there dead in the box and I can't bring myself to throw any money at it. Good luck with yours. I sure love these machines, and just wish parts were even a little more affordable...it's kind of sickening to me, the idea of throwing out even just a screen that big that still works!

So...

Trying to finish a Project in Photos sent this machine into fits - however, I learned many things.

It is a heat problem, and the problem is the Nvidia GT130 card. There are several threads in this forum about an "unacknowledged" problem with the Nvidia GT130 cards and the drivers. One thread stated that Apple was quietly replacing the GT130 with a revised version of the card - but you had to know about the problem and pursue it. Too late for me. Secondly, the drivers included in each newer iteration of OS X compounded the problem, basically causing the card to overheat. Seems a shame that neither Nvidia or Apple chose to look into this and update the drivers. The forums are full of plaintive moans hoping that OS X 10.X.X would be the fix for this driver problem.

I also followed a thread related to the above threads that mentioned that El Capitan would slow your Mac down if you have malware (assumingly, unbeknownst to you). When I installed El Capitan, after reading great reviews about how improved the speed of their systems, I installed it and my system bogged down - horribly.

Anyway - I threw in the towel, made an El Capitan installation USB drive, blew the whole thing off and reinstalled. Twice. The first time, I migrated some crap over - big mistake. Machine turned into a pretty rock once again. Second time - clean install, migrated nothing. I have installed most of the apps I use regularly - Office 365, Photos, Steam, Battle.net, Pixelmator and smcFanControl and the mac couldn't run better. Still gets hot when using Photos - hit 73C - but not near the 92C it hit when I was saving a Project as a PDF. Phew!

One thing many of the forum contributors mentioned was how this problem went away under Windows - better drivers. When I get my new iMac (if they ever announce it!) this little baby will become my wife's Windows machine.

So, when you say 'too late for you', do you mean just that your machine didn't come with that updated card, or that it can't be had? As for me, I take back everything I said. I think I had dumb luck for a day, totally coincidental, and now random shutdowns have resumed. It does feel like heat, so I'm interested in what you'd said about drivers/Nvidia, etc.

If you search for GT130 and kernel panics, you can probably find the thread. But assuming that all these pieces are in place, then I would say I don't have the revised GT130 (those that did get it say the problems were resolved) and it is my understanding that you can't get one now except from third party vendors (and most I found were used - the one new one was $400 - price of rarity).

Since I did. Y clean reinstall action, my Mac only shuts off now when I'm using Photos (I have a lot of high res pics - possibly taxes the vid card?). Everything else runs fine. I did not do a migration of my files and data because the first time I tried this, and it migrated the slowness and multiple daily crashes as well.

Thanks. I finally installed smcfancontrol, as well (on this iMac and a MBP), and yeah, there's some heat there. I haven't - knock on wood - had a shutdown since installing it yesterday, and it had become pretty chronic. Photos, yes, and I run the CC apps pretty hard, Illustrator and Photoshop, as well as Lightroom, and it feels like the first two anyway were pretty prone to taking it down. Hardware? Software? Combination, producing heat? Don't know, but pretty frustrating. I'd certainly trade having a ridiculously slim case for stability; maybe this fan control will carry me for a while.

I surrender.

This will be my last post on this issue, so to those of you enduring the sudden blackness that hits you in the middle of your computing tasks, I wish you luck.

My mac just shuts off almost constantly now (not an unexpected graceful shutdown, but an honest to goodness "It's on -It's off". I'm pretty sure the problem was/is heat. I think it reached the point where the heat has caused permanent damage to (insert component name here). From what I've gathered for this model (early 2009 24" iMac 3.06 GHz GT130) it is likely the graphics card coupled with the poor drivers included with later iterations of OSX (that neither Nvidia or Apple cared to address). Other readers have suggested that the drivers included post-Lion cause the graphics card to get HOT (I hit over 90C). For me it occurred mainly with graphics-related apps. Photos just kills it, iPhoto not so much, but even iTunes in Album display will bring it down (I have A LOT of music in this baby). The driver idea rings true with me because the machine DOES NOT crash in Windows 10. Never. Better drivers?

I'm patiently waiting for the release of the new iMacs (hopefully October) but what has me worried is the number of posts on these forums from people with the same issue on macs as new as last year's model, and the fact that NONE of them seem to get any resolution to their problems. I have three Windows machines in this house, and when things go south, it's pretty easy to pop in a new whatever and be on my way again. This was a top-of-the-line iMac at the time of purchase and I started having issues in the 6th year. Sure, you might say well, gee, its six years old, time for a new one and you'd be right. However, my oldest PC is 10 this year and it may be old and slow (those are reasons for upgrading/replacing) but it STILL WORKS. It just didn't decide, after six years, to become a very expensive paper weight, and it cost 1/3 the cost of this mac.

So when I drop my $4000CAN on a new top-of-the-line iMac, I will always be wondering "Is this the time that it's just going to die?" The vaunted Apple quality is a well-perpetuated myth, I think.

I had the same issue as many others here but actually found the solution.

I made a Genius Bar appointment after I tried all of the tests and other great info in the community, but nothing seemed to work. I even bought a new power supply but that didn't help either.

When I took it in they did a quick test and found it in 30 seconds! I have a 3TB fusion drive and the hard drive failed so every time I would "labor" the machine or it would require writing items to the hard driver, like iphoto and photos it would crash.

Because its outa warranty but a known issue I will pay for service and they are standing behind the parts, like the HD.

And that boys and girls is why I only have Apple products........great service!

Problem solved.

I’ve never asked fot that kind of problem.

If so it is a mistake.

Can your emove me from that list?

THANKS.

Danny LAUWERS

Bergensestwg. 143/5

B-1600 St-P-Leeuw

mail: danny.lauwers3@telenet.be

phone: +32 488 270 399

Annnnd...my machine is just flat blacking out again (turning off, to be clear). Not as often, but way too often. It always requires pulling the power cord for 20 seconds or so (presumably resetting SMC) to boot again; will never boot without doing that after a crash. A.C. has given in (and I don't blame him); I'm not asking for or expecting a response.

I guess I'm not ready to be fully convinced it's solely hardware. Hardware test shows nothing, I don’t get errors with the drive, and the temperatures never appear to exceed maybe 120 degrees (F).

So I’m wondering how many of you happen to use any of the following non-Apple apps, just out of curiosity: Xmarks, any Adobe Creative Cloud and its multiple processes, Canon EOS apps, Avast, Dropbox, OneDrive, SuperDuper, Canon MF (printer/scanner), LeapFrog (kids toy updater), or Wacom tablet apps. There are many more, but these are things that are at least always running something in the background on this machine. If there's some correlation, you know, I'd sure like to know it…the temperatures as I said aren’t bad at all, particularly with smcFanControl cranking away, so perhaps there's just some app or drive taking the whole thing down. Yes, I'm grasping now, but I'm pretty frustrated and would love to solve this thing.

Dropbox and OneDrive - I anticipate a crash whenever I use these apps and i am usually not disappointed, but if I keep the activity low, I usually make it. Same goes for mail - Apple Mail and Outlook. That's why I originally wondered if it had to with online activity before I decided heat was the issue, again before I decided I didn't know *** is wrong with this machine. Photos is a guaranteed crash.

I am planning on turning this into a Windows box when I replace it. It is perfectly stable in Windows.

In my grasping at straws I put Sierra on this iMac, a few days ago. Figured I have little to lose, though I was concerned that it would stay 'on' long enough to complete the update. It did, no problem. Two observations:

-Temps generally creep higher;

-I have not had one single shutdown/blackout since installing - this going from guaranteed every 20 minutes if running anything intensive. I've run my most angry apps, heavy lifting Adobe stuff, kept Photos, iTunes and Mail open, the whole thing, everything chugging away, rendered a decent sized movie...and it hasn't blinked.

Maybe coincidence. Or not. But I'm a whole lot happier, and hoping it lasts.