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

Tank9

Level 1

0 points

Mar 30, 2011 5:29 PM in response to Berry with an A

Hi, It's tank nine again. I came back to report zero shut down from heavy use on my iMac with 12gb Mushkin. I watched a 4K video on YouTube, still no shut down.

Mar 31, 2011 1:09 AM in response to Jeff Donald

Well it seems that not all new OWC ram works with 16 G.
See this copy of a post:

Bad news... just had a shutdown (since installing the NEW OWC 16GB memory). Bummer. We'll see if it >is any more or less frequent and/or if I need to try the 12GB route.

http://discussions.apple.com/thread.jspa?messageID=13313974#13313974

peterwillem

Mar 31, 2011 11:27 AM in response to peterwillem

Could be another issue such as OS or software. In any event, this is the only case of "tweaked" OWC ram possibly failing, since the tweak in Mid(?) December 2010, on the forums I frequently visit. Just one reported failure in 3 1/2 months is strong evidence that OWC ram is working at 16GB.

Firebush

Level 1

4 points

Mar 31, 2011 2:57 PM in response to Berry with an A

Crucial customers: Just got off the phone with helpful tech support at Crucial.com where 8 of my 16gb RAM came from. He acknowledged a recently rebuilt module and they are replacing my 8gb purchased last November. Not incredibly hopeful, but I would sure like to use all 16gb of memory on this thing. Will report my success/failure when new memory installed.

Apr 1, 2011 8:03 AM in response to JohnnyVega$

Just to update - I had upgraded my RAM from an outside source (16GB) since I was able to purchase the RAM at 1/2 price and install it myself. I replaced the RAM and it solved my issue. The company I bought the RAM from explained that because my Mac was running so much RAM that it becomes very sensitive and the slightest problem with one of the memory sticks would cause a voltage problem that would cause the shutdown. My mac has been running fine for a long time now.

Apr 1, 2011 8:05 AM in response to Berry with an A

I had the same problem with Safari when I first upgraded to 16GB of RAM. I don't use aperture. It turned out to be a bad memory stick. See my previous post and update.

Apr 1, 2011 8:07 AM in response to Berry with an A

I had the same problem with Safari when I first upgraded to 16GB of RAM. I don't use aperture. It turned out to be a bad memory stick. See my previous post and update.

Apr 7, 2011 9:28 AM in response to mountainlady

Same problem with my iMac, no help from tech or customer service personnel. Was told "we will look into it" Wish they would have informed me of this before I bought the thing.

MattOC

Level 1

0 points

Apr 7, 2011 9:40 AM in response to Firebush

UPDATE: I also just called Crucial. Support rep said he'd never heard of such an issue, and said I should run RAM test programs on each of my two 4 GB sticks (4 GB Apple RAM + 8 GB Crucial RAM = 12 GB Total - it happens on us non16GB folks too). He didn't seem like he thought it was a RAM issue - said it could be firmware, hard drive, etc.

I'll run the tests later on each stick and see what I get but I may ask for replacement 'just because'.

Tank9

Level 1

0 points

Apr 7, 2011 11:09 PM in response to Tank9

Okay I am back to update you guys on my Mushkin ram. I was surprised to come back home from work today to see a Mushkin box on the table. Mushkin went ahead and sent out new ram. As the representative said the company decided to replace the old chips with Hynix chips on them.

If any one wants photo proof I can upload The Mushkin ram with Hynix chips to photo bucket or some place.

I now have 16GB installed and will test it out and report back.

Firebush

Level 1

4 points

Apr 8, 2011 12:29 PM in response to Berry with an A

So, I did, in fact, receive and installed replacement RAM from crucial at no charge. Problem persists. I just returned from an appointment at the local Apple Store where they diagnosed a faulty graphics card. The have ordered a new one and will replace it -- 5 days or so.

NOTE: The way we diagnosed the problem was the fact that, when attached to my secondary Cinema Display, upon startup I consistently got a strange, pixelated screen before the login prompt. Coupled with my other graphics-related shut-down issues, this was the first line of attack. I am hopeful. Will report when I have results.

Tank9

Level 1

0 points

Apr 8, 2011 1:59 PM in response to Berry with an A

I am not saying that anyone should rush out and buy the Mushkin Hynix Enhanced 2x4GB ram for Apple yet, although the price did drop. The updated Mushkin with Hynix chips are doing quite well so far. I used Firefox and Adobe Premiere Pro CS5 simultaneously for 5 hours. Played Portal on maxed out settings on everything for 2 hours. Then used Photoshop CS5 and edited huge AVCHD videos in Premiere simultaneously, with no shut down thus far. Then Youtube, email, ect.

That's pretty intensive. I'll keep everyone posted.

Apr 10, 2011 10:04 AM in response to Berry with an A

Can't believe it. Reading through the issues here about random shutdowns now reinforces my fear that this iMac is flawed. First noticed that my iMac was shutting down after going in to "wake" it from sleep in the morning. Power button would NOT turn it on. I would switch it to a different outlet in the surge suppressor. After 2-3x of this behavior, I went and invested in a $150 APC with ample power to run the iMac thinking it was a power issue with the surge suppressor. In the last few weeks, I have experienced the same problem--iMac is off at random times, power button won't restart it. I change it to a different outlet in the APC, and then it will power on.
This is a factory-original--I have not installed any RAM or other hardware peripheral.

It is only 6 months old--wondering what--if anything--Apple would do if I take it in?

icazzi

Level 1

4 points

Apr 11, 2011 8:08 AM in response to Berry with an A

Add another iMac user to the list experiencing this problem. Here are my specs:

OS : 10.6.7
Identifier : iMac 11,3
Proccesor : Core i7
Speed : 2.93 Ghz
Num. of Cores : 4
Memory : 16Gb 1333Mhz ( Aftermarket OWC )
BootRom : IM112.0057.B00
SMC ver.: 1.59f2
HDD: Hitachi HDS722020ALA330 2TB
Graphic Card : ATI Radeon HD 5750 1Gb

MattOC

Level 1

0 points

Apr 11, 2011 10:40 AM in response to Berry with an A

Third shutdown since January with daily computer usage. Last one was two weeks ago. 12 (not 16) GB of RAM

What are people getting when they call RAM or APPLE support?

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

27-inch / 27" iMac Random Shut down