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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 24, 2010 4:40 AM in response to Dextercitox

Well I have a different experience. I use all the banks with 12 G of ram and no shutdown problems.
When using 16 G ram in all the banks the shutdown problems return.
Read my earlier posts on this.

peterwillem

Nov 25, 2010 1:05 AM in response to peterwillem

i have two equal 27" i7 imacs. both habe 16GB (4x4GB) of ram. one machine shuts down randomly, the other machine works fine.

kfiller

Level 1

4 points

Nov 25, 2010 1:17 AM in response to spikehansley

@spikehansley

Are you using OEM or aftermarket memory? Maker? A friend bought a 27" 11,3 iMac two weeks after I did, with the exact same specs. He is using the same Corsair memory, without issue.

I guess it depends on how lucky you are.

Nov 25, 2010 9:23 AM in response to Berry with an A

i bought my iMac 27" Intel core i3, 4GB(2x2GB), early November. I got the same problem as you all mentioned. It just shutdown suddenly after i used it for an hour. After that, i tried to turn it on but it don't have any respond. Then i tried to unplug the power connection from the imac n reconnect it , then the imac can start up again but it still shut down after few minutes! I was so disappointed that this brand new imac make me feel sad n my projects were pending due to this unexpected problem.

I called to Apple Assistance and he asked me to do some reset but still failed. Therefore, i sent my imac to the apple service center for checking on last friday.

Today, I got a new set of iMac 27" for repalcement. Hopefully, it won't give me the same problem again. I really love Mac 🙂

Satoneko

Level 1

15 points

Nov 25, 2010 3:06 PM in response to Berry with an A

I am joining you people in the brother/sisterhood of iMac random shutdowns. I have a build-to-order iMac 27” 2.93 GHz Intel Core i7 (1 TB HDD, 8 GB memory) purchased online in August. The memory I have is 4 x 2 GB installed by Apple. The shutdowns started in the first week of September, approximately one month after purchase. First, I thought it was due to excessive heat, because it was a particularly hot summer. The problem continued to occur about once a week. It happened while I was browsing Safari, watching YouTube, working in Office, etc. which are things that don’t necessarily tax the CPU or memory. I’ve done SMC and PRAM resets, and AHT showed no problems.

In the beginning of November, I called Apple who told me send it to an Authorized Service Provider. The service kept the machine for 18 days. The shutdown never occurred while it was in repair, but the repairman changed the power supply unit, just in case. So last Saturday, the iMac was delivered to my office, I set it up, turned it on, and in 15 minutes it shutdown. I called the repairman who simply could not believe that it shut down and claimed, “I tested the power supply unit, memory, logic board, etc. and there is nothing wrong with your machine.”

At that point, I suspected power flux in my office (although I use a surge protector). So, I called an electrician to check the power outlet and wirings. He found nothing wrong, and my surge protector was functional. He did mention that there might be some electrical noise that gets past the surge protector, and mess up some exceptionally “sensitive” circuitry in the iMac. Considering the fact that I’ve been working in this office for almost 20 years and have used other Macs (including late-2006 iMac) and electrical appliances without any problem, I think there is some component in the mid-2010 iMac (or recent aluminum iMacs) that makes it very susceptible to micro-surges or noises.

The shutdowns continue to happen and it is … annoying. So, I am at a loss of what to do. Install an expensive hospital UPS? Hey, if anyone at Apple is reading this, I really hope you do something about this. Other than the shutdowns, it is a gorgeous computer. Fix it, PLEASE.

Nov 25, 2010 8:50 PM in response to Dextercitox

Random shutdown here when idle. iMac 27" Core i7 4G Ram stock except for trackpad. Bluetooth keyboard.

Nov 26, 2010 7:16 AM in response to BobDrummer

Until recently the shutdown problems were caused for 99% by using 16 G of mostly 3rd party ram.
The last couple of days a lot of people joined this forum and these threads with shutdown problems on their mid 2010 iMacs with ram varying from 4 to 12 G and of all sorts of brands, including Apple installed.

If it were not Mac computers we are talking about I would think of a virus infection???

peterwillem

Satoneko

Level 1

15 points

Nov 26, 2010 5:38 PM in response to peterwillem

I really have a feeling that this is not a virus or software problem but a electromechanical issue. I am getting a feeling that it may be static electricity build-up. This feels so similar to the PowerMac problem (I owned a G4 Quicksilver) when the computer suddenly shut down or wouldn't wake up from sleep. That was caused by a faulty PSU. Hope someone with more knowledge of electronics will figure it out.

kfiller

Level 1

4 points

Nov 26, 2010 5:52 PM in response to Satoneko

I concur with satoneko - there are people here that have the stock config 4GB, all the way up to 16GB encountering the problem. Then, there are others with identical hardware/software configurations that have no problems whatsoever.

At the end of the day, the problem is likely some sort of logic board / power supply issue that only intermittently affects certain machines. We may think it's related to memory, as that is the only real hardware configurable option we have to work (unless you pop off the glass and start poking around the inside).

kfiller

Level 1

4 points

Nov 26, 2010 5:56 PM in response to Satoneko

@Satoneko - do you use the green ground cable attached to the power cord that Apple supplies for Japan hardware? I am also in Japan, and I currently do not have the ground cable properly attached to the surge protector. Perhaps it's time for a new surge protector.

JDI

Level 1

0 points

Nov 26, 2010 6:21 PM in response to kfiller

I posted about the same problem I was having with a 27 inch late 2009 IMAC I-5 on November 14. I was running only 8 gigs of memory. When the problem reoccurred, I reduced it to the original 4 gigs.
After trying everything on these forums, I brought it into my local Apple store last Tuesday.
At first all the tests came out normal. They then did a long term test and the machine failed on them. They feel the failure is in the logic board or the video card. They are replacing both and I should have the machine back in a few days. I will let the discussion thread know the results.

Satoneko

Level 1

15 points

Nov 27, 2010 3:58 AM in response to kfiller

@kfiller: No I do not connect the green ground wires. I asked that exact question to the electrician and he said it doesn’t really matter. Millions of the people never connect those ground wires and never have any problem (that’s what the electrician said). If the loose wires bother you, I believe there is a connector plug that you can attach to convert it into a three-prong connector. This raises an interesting point, though.

Today, I talked to a consultant of the Tokyo Electric Power Company (TEPCO). He suggested that the problem may be some sort of power surge, but since other electronic appliances (particularly the old iMac 17” C2D) in my office are unaffected, he thinks that the problem is in iMac 27” itself. However, he also indicated that I live in an old apartment building built around the end of 1960s, and it may not have proper grounding. Buildings built after 1975 in Japan are required by law to have the inbuilt ground wires in the main wiring and in all power outlets, but I may not have that. I’m having a TEPCO electrician come in next week to check it.

So, proper grounding may be a solution. However, both the local electrician and the TEPCO consultant said that a computer should not shut down just because it is not grounded, because modern electronic appliances usually have sufficient insulation against daily noise and static. I still think the aluminum iMac has got a configuration that makes it susceptible to power surge or static electricity.

Nov 27, 2010 4:00 AM in response to Satoneko

You maybe right, but I have some doubts about it. If it were a electromechanical cause it should happen independently of the amount of ram. Than why do I, and a lot of others, have this problem only when using 16 G ram?

peterwillem

liddown

Level 1

4 points

Nov 27, 2010 2:43 PM in response to Berry with an A

We have been suffering with this random problem for almost a year (yes looks like I will have to buy the extended warranty). This was a new i7 shipped directly from China to us in Colorado in March of 09. This is not a heat related problem for us, no external connected... In reality this computer sits in our kitchen and get only moderate use for email, iTunes, and web... Seems to happen mostly while using Safari... We can hear what sounds like a relay click, and then black screen... Only way to get going again is to press the power button... Just shuts off, no warning, no rhyme or reason....

Specs:
Model Name: iMac
Model Identifier: iMac11,1
Processor Name: Intel Core i7
Processor Speed: 2.8 GHz
Number Of Processors: 1
Total Number Of Cores: 4
L2 Cache (per core): 256 KB
L3 Cache: 8 MB
Memory: 8 GB
Processor Interconnect Speed: 4.8 GT/s
Boot ROM Version: IM111.0034.B02
SMC Version (system): 1.54f36

Satoneko

Level 1

15 points

Nov 27, 2010 4:00 PM in response to peterwillem

@peterwillem: I have 8GB memory (4x 2GB) installed by Apple, and I have not touched them since I received my machine in August, and have this problem. So I never had 16 GB memory.

Now, I assume majority of the people who purchased this sophisticated spec will want to put in maximum memory to get the most out their machines. Then they encounter the shutdown problem and reduce the RAM and seem to have solved the problem. If that is the case, that is an interesting hint. But for me personally, that's not the case. Remember, I've already sent my iMac in for repair and they've declared there's nothing wrong with the hardware, and that's why I'm trying to figure out whether it's something in my office, something in the iMac, or some combination that's causing this.

27-inch / 27" iMac Random Shut down