Why is my imac shutting down by itself?

I went through this two years ago with my 21.5 12,1 and after wrangling with the Apple Store folks for a month or two, they put in a new power supply which has lasted until now, when the problem has just started up. Since it seems to be all over the place -- memory, hard drives, mother boards, power supplies, etc. -- i'm thinking it may be a combination of factors. I've also had my screen replaced twice because very fine dust gets in and permanently mucks up the screen. I can only assume it's affecting the fans and cooling. It's coming from my pellet stove which I need in the winter as it's my only heat.

I did notice that the power failures started with a heavy graphics load, watching Netflix, downloading large graphic files, photoshop, and that other on this thread have mentioned similar happenings, so I'm wondering if the graphics load could have something to do with it? Or some combination of factors involving graphics, dust, wonky power supplies and even screen connections are shorting the system out.

One thing I do know is that after four years of uninterrupted problems with this problem, Apple should have some idea of what's happening. And they don't, or at least they are not sharing. As a user since 1988 and fully dedicated to the platform with tens of thousands of dollars in software and hardware I would not give it up lightly, but between the power failures and the constant inability to operate a stable office network (NAS dropouts, network dropouts, PC interfacing), I'm almost ready to throw in the towel. I cannot work on deadlines (publishing) with flakey, undependable tools. I run a five-mac office network and three peripheral at-home macs that join into the network that has two NAS machines and several other backup/dedicated (fonts, photos, etc.) drives. But that's another problem; one more of too many, these days.

Dir -- you only need to unplug it - both ends! - for about 1 minute. Then plug it back in, wait 5 seconds and restart.

I have been having exactly the same issue -- well, minus the stove pellets ;-) Really bad. I've run all hardware tests and removed 3rd party RAM. It does seem to be worse when i'm giving the cpu, or graphics card more work. I can sometimes go a day or 2 if no pro apps are used. Apple really needs to trace this out.

James Hall5 wrote:

I have been having exactly the same issue -- well, minus the stove pellets ;-) Really bad. I've run all hardware tests and removed 3rd party RAM. It does seem to be worse when i'm giving the cpu, or graphics card more work. I can sometimes go a day or 2 if no pro apps are used. Apple really needs to trace this out.

It is because of faulty hardware. What that hardware is can be different in each system. No computer shuts down by itself if all parts inside it are working properly.

For my machine, it is a power supply problem. I will replace it myself and hope for the best ($140 vs a new machine)..

how do you know Jay?

I had the same issue - thanks this should fix it. It was set to 10min by default after the recent update.

I really don't , but it's almost identical to the problem I had two years ago which went away until now with a new power supply. I'm just hoping.

I have same issue. My imac was fixed 2 weeks ago (when it was switching itself off after few seconds) - power supply issue. I played elder scrolls online when the problem occurred again. I turn it back on, and after 15-20 mins it happened again. I went to Apple and since they had no engineer at that day (but about 12-15 salesmen), the first available appointment was for Tuesday (6 days...). so I took it to authorised Apple service (when it was "fixed" last time). very, very, very disappointed. I use it professionally and cant meet deadlines, because last time took them a week to repair and who knows how long I will have to wait this time.

Are these problems isolated to iMacs only?

Authorised Apple Service tested my imac for 25hours and did not find out what was wrong with it. I took it back home only to find out that that after 30mins problem occurred again. I took it to the Apple directly. They have replaced logic board and called me that it its fixed and ready to collect. I took it back home only to find out that is hasn't been fixed at all.

very, very, very disappointed in Apple. every

I have invested for the want of a better word a lot on money in Apple products. I hear more stories of poor service each day. It's quite a worry.

That's because it's the power supply, and Apple knows it. I'm on my third one now. This time, when it started happening again, I ordered a new supply for $130 plus tax = @ $150 and followed the YouTube instructions to replace it. Worked like a charm. fire up fast and stays on for three weeks now. Not all machines are easy to fix -- this one has a short cord between the screen and the logic board that's really hard to reattach when you are putting it back together, but patience wins out and it is doable.

I don't know if the units themselves were/are deficient or something in the logic board is blowing them up, but it IS the power supply and nothing is going to work until you replace it.

Good Luck!

Jay Gamel

Jay,

I'm curious. Why do you attribute it to the power supply? If you keep replacing the power supply and the problem continues, that would tell me it's NOT the power supply.

As I posted either in this thread or in another one, although a lot of people are saying the machine is "shutting off" or "powering down," I found that not to be the case. Although the machine appears to have lost power, it actually hasn't. If I put my hand on the back of the machine where the power button is, I can feel either the fan or the hard drive spinning.

And if you read enough of the posts about this problem, you'll find that everyone has a different answer to the problem ... but none of them work. Also, the age of the machine appears to have no bearing on it. People with new machines have the problem, but it didn't start on my iMac until it was seven-and-a-half years old.

It really is hard to believe that Apple doesn't know what's causing it. They sure are remaining awfully quiet about.

Bob

Robert Golden1 wrote:

Jay,

I'm curious. Why do you attribute it to the power supply? If you keep replacing the power supply and the problem continues, that would tell me it's NOT the power supply.

Because over time the power supply starts to fail. Replacing it fixes the failing parts in it.