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27-inch / 27" iMac Random Shut down

SPECS:____________________________________________________________________________
• 27" 2.8 GHz Intel Core i7 / 8gig / 1TB
• OS 10.6.3 (about to update to 10.6.4)
• All firmware updates have been applied according to software update
• 3 external drives: 1-320 gig 800fw / 1-TB USB 2.0 / 1-500gig USB 2.0

INFORMATION:____________________________________________________________________

I've been running with this configuration ( 3 extra drives) since approximately December with no issues. Out of the blue... only running Aperture and Safari - my iMac JUST SHUTS off- WITHOUTwarning. It acted as though I was running a MacBook and the battery going dead/asleep. That's how random and sudden it shut down - NO WARNING. I did have the iMac asleep for about three hours before coming back to it to start working again when it shut down, but it should have even been cool.

I only started reading around on the web to see of other incidents after this random shut down this evening, but I can't find anything specific. I've found A LOT of similar things - all seemingly related to "HEAT."

And heat seems to be a certain issue recently - in the last day or two. Today I noticed my top back side to be hot, which isn't uncommon, however, it became so hot I really wasn't able to keep my hand on the top back. I've also noticed A LOT of spinning beach balls, and lots of processor delay! Heat??

There are NO energy saver pref's set to automatically shut it down. The power was and is firmly set. There are no network settings, nor access to the iMac to have it shut down. It is not shared with anyone on the network.

SUMMARY:___________________________________________________________________________

• Today, I grabbed a couple temp / monitor widgets and am trying to watch the data. All components seem to be at/around/below 140 degrees F with ambient air at 77 degrees. I don't know numbers, but that all seems reasonable.
• Going to update to OS 10.6.4 (doubt that's it!!)
• I'm going to run the hardware test from my disc to see if ANYTHING. 8-p
• AND... I'm going to call Apple to set up a case. It's still full under warranty, and I have 2 more years of AppleCare on it. But there's been too many things pointing to hardware to call this a software issue.

I've dodged all the display issues with my iMac, but now.. I'm a bit hacked knowing how much I spent on this thing, with the initial DELAYS I went through, ordering it before it had even been released!

?? QUESTION ??_____________________________________________________________________

So, has anyone else been having this issue, heard of a solution, seen anything on Apple's website of known issues ??

Barry
( Grumbling bout my Mac)

Which one of twelve??, Mac OS X (10.5.6), ever hear Newton?!! ;-) One of those, too!

Posted on Jun 22, 2010 8:59 PM

534 replies

Nov 29, 2010 8:11 AM in response to Berry with an A

I am having the same issue. Bought a CUstom 27-inch i7 iMac 2 months ago, added 3rd party memory to increase to 16GB, random shutdowns. Removed memory to stock apple 4GB, still had random shutdowns. Bought AppleCare, had Apple replace my iMac with a new iMac, added 16GB of OWC memory, was stable for a month, but since have had 4 random shutdowns. Two happened today, losing 6 hours of work on the first shutdown. This is ridiculous and Apple needs to address this obviously defective product!!!!

Gradenko

Level 1

0 points

Nov 29, 2010 6:57 PM in response to Berry with an A

I have this problem too. It started after installing 16GB PC10600 1333MHZ SO-DIMM kit from OWC into a 27" i7 Quad-Core 2.93Ghz. Thought it was my UPS so connected iMac direct to wall socket and it still occurred. It appeared to be random at first, but I can now make it shutdown without fail by loading iMovie and running "Analyse for Stabilization" on a short clip.

Will try pulling out a SO-DIMM and see if it still happens. Apple better have a fix for this coming - I need 16GB and would have got a Mac Pro if I'd known about this.

Nov 30, 2010 8:22 PM in response to Berry with an A

ISSUE: ________________________________________________
iMac shuts down WITHOUT warning

INFORMATION: _______________________________________
• 27" 2.93 GHz/ Intel Quad Core i7 / 12GB / 2TB / OS 10.6.5
• All firmware updates have been applied according to software update
• 3 external drives: 2-TB Netgear stora / 2-TB USB 2.0 Fantom / 2-TB USB 2.0 WD

I have the same problem. It's a nightmare. I bought my iMac (27'' i7 2.9Ghz 12GB 2TB) on august 2010 and it has shut off randomly without warning 17 times in 14 weeks. Sometime, i was surfing on the internet, sometime I was using iMovie or iPhoto. I went 4 times at apple store but they have never repaired it because they can't reproduce the problem. Since I have my iMac, it was on reparation over 17 days on 120.

They don't want to replace my narcoleptic iMac with a new one. It's my first imac and begin to regret to have switched from windows. I already had a problem with a Dell computer. I called and the day after I received a new computer. I don't understand why Apple don't want to replace my 3 months iMac. I loose my time to explain, make backup, pack, go to store, unpack, format, install.They asked me to plug my computer in a new room! I have done but it shuts off. Buy a battery backup! Disconnect all USB devices. What's next? In fact, they don't know what to do.

I'm sad because I thought that Apple is a good company. This morning they changed the power supply. i hate this computer.

Dec 2, 2010 6:06 AM in response to Berry with an A

I'm having the same issue with my 27" i3, twice (so far) it has shut itself down and has been difficult to restart. Very cold morning inside the house and the computer had been idle for a long time. This time I had just woken, used it to check FB for a couple of minutes, left to cook myself some oatmeal and then came back to do something else and it was off. Doubtful about my particular case being temp related, it's nipply in here.

Dec 6, 2010 7:46 AM in response to Berry with an A

Well I'm another having this problem happened to me twice yesterday while surfing the internet with Safari. Very aggravating when it happened a few days ago and I lost about 3 hours of writing in pages. Anyone get any kind of a resolution from apple in reference to this. Do they look at these posts?

Dec 6, 2010 8:00 AM in response to JohnnyVega$

Anyone get any kind of a resolution from apple in reference to this. Do they look at these posts?

None so far and officially no.

peterwillem

Dec 6, 2010 8:17 AM in response to JohnnyVega$

Hi everyone, I'm a little late to this thread but would like to point one thing out - are the people having problems with their iMac actually using UPSes with AVR? Quality of voltage in grids vary in places and many electronic devices work much better if they are attached through a UPS that has AVR (voltage regulation, so that you get a clean and stable voltage sinusoid).

To back my words with some real life stories: a few computers and a laser cutter at the company i work for had been behaving erratically (shutdowns included, the cutter made mistakes in cutting) until we changed the UPS to a new one that happened to have AVR. All problems gone now.

Dec 6, 2010 8:34 AM in response to adamkozlowski79

Quality of voltage in grids vary in places and many electronic devices work much better if they are >attached through a UPS that has AVR (voltage regulation, so that you get a clean and stable voltage >sinusoid).

If this is the cause, would it not effect all iMacs with various amount of ram?
At this moment most iMacs, with or without UPS/AVR, and less than 16 G ram have no shutdowns.
Besides this issue has been discussed in other threads as well.

peterwillem

Dec 6, 2010 10:54 AM in response to peterwillem

peterwillem wrote:

Quality of voltage in grids vary in places and many electronic devices work much better if they are >attached through a UPS that has AVR (voltage regulation, so that you get a clean and stable voltage >sinusoid).

If this is the cause, would it not effect all iMacs with various amount of ram?
At this moment most iMacs, with or without UPS/AVR, and less than 16 G ram have no shutdowns.
Besides this issue has been discussed in other threads as well.

peterwillem

The UPS is not the solution. I use a MGE Pulsar 1000, it has AVR, and i have shutdowns.

Also, take note that i have 8Gb and also have shutdowns, so the problem isn't the 16Gb amount.

Dec 6, 2010 3:20 PM in response to Dextercitox

Also, take note that i have 8Gb and also have shutdowns, so the problem isn't the 16Gb amount.

I said MOST iMacs. So there are some,including yourself, who apparently do have shutdown problems with less than 16 g ram.
That can well be caused by other problems, like bad ram.

peterwillem

Satoneko

Level 1

15 points

Dec 6, 2010 4:41 PM in response to peterwillem

@peterwillem

I think you are giving a wrong impression that the shutdown problem is a matter for only those with 16GB ram. But like several others including myself, there are those using less amount of ram. I imagine that the bias comes from the fact that a large number of people who purchased this high-spec iMac has added rams themselves, and many have put in the maximum 16GB.

As of now, I've sent my iMac back to the authorized service provider to check it out again. I really hope they find a remedy for this. If not (i.e. if it is some inherent design flaw in the circuitry), I hope Apple can tell us whether WE can do something (such as use ram from certain manufacturer, use specific UPS, etc.) so the shutdowns occur less frequently.

I love Macs so much that I am willing to live with some flaws, but since I use my iMac for work, frequent shutdowns are unacceptable.

Dec 7, 2010 5:49 AM in response to Satoneko

@ satoneko

I think you are giving a wrong impression that the shutdown problem is a matter for only those with >16GB ram.

This is not what I said. I said the majority of the people in these threads have shutdown problems when using 16 G ram. For MOST of them, myself included, they stop when using less ram. (14, 12 or 8 G). Mind you most of them, so not all of them! Besides there are people with 16 G ram who do not have these problems. Not to speak of the unknown number of people who who may have or may not have these problems, but of whom we don't know about because they do not post in these threads.

peterwillem

Dec 7, 2010 7:22 AM in response to peterwillem

We've got two i3 iMacs that are experiencing some odd symptoms. Random sleep / shutdown that wont allow wake up without hard booting. Not a great problem to be having. Both systems are running on UPS and our third 21" seems to be having zero problems. Not sure what is causing this but may try to reinstall OS and see if its software related.

Dec 7, 2010 7:36 AM in response to skeltonmedia

Looks like the same problem. First how much ram and what brand are you using?
Reinstalling the OS is probably the first advise AppleCare or such will give you.
It did not help me a bit, and many others as well.
If using 16 G ram, try using 12 or 8 G.

peterwillem

The hatter

Level 9

61,001 points

Dec 7, 2010 7:47 AM in response to peterwillem

Just ran across this, had a few thoughts... is this always with Core i7s (4 cores, 8 threads)?

The Mac Pro 2009 suffered from spikes in temperature when using any audio type applications, going from 35*C all the way into 80's.

Inrush current plagued numerous Mac Pro models, which really only had 4 or 8 cores (and 8 to 16 logical cores). Wake from sleep freezing in Early 2008 Mac Pro was addressed by firmware updates to EFI and SMC.

The iMac is often compared to, or a lot of people ask, if iMac or entry level Mac Pro fits their needs with the advent of a quad-core / 16GB iMac.

A true sine wave UPS with 1000VA, 1300-1500VA for models with AVR), is what Mac Pro (and G5s from 2003+ ) required. Could that be hidden danger tripping up iMac?

Core i7s can kick up a lot of heat, witness the large heatsinks employed, or how poorly the included Intel one that comes with the Core i7 920 was. iMac is perfect for a lower power mobile and Sandy Bridge.

Maximum Memory: The DDR3-1066 based iMac Intel has a system maximum of 8-16GB. The 2 slot versions (Model ID 9,1) have a 8GB max, and the 4 slot versions (Model ID 10,1 and newer) have a 16GB max.

http://www.ramjet.com/imi.asp#1066

What happens to the directory and file system as a result of those freezes? it needs repair (safe boot, fsck, disk utility, etc.), or you compound the problem with more issues.

It took a couple months to realize there was a problem with Early 2009 Mac Pro (4,1) and that it was audio-induced, and another 4+ months for a "patch" to address some of the behavior and problem after it got increased attention.

27-inch / 27" iMac Random Shut down