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 3, 2011 12:45 PM in response to JANSJE

JANSJE, when a video card fails it is quite different from a sudden shut down as the computer still runs but the screen is off. Laptop video cards sometimes fail when the GPU and CPU share the same heat pipe. Due to too much heat the GPU usually comes loose, thus the screen turns off.

Mar 3, 2011 4:29 PM in response to peterwillem

First random shut-down occurred tonight. Very odd. I wasn't doing anything that would have taxed the system either. I'll continue to monitor and update this thread. If it happens again - I'll remove 4GB of ram and go down to 12GB to see if the situation improves.

Again, at this point one random shutdown. The only other issue I've come across with my 27" iMac iCore 7 system is the bluetooth keyboard seems to disconnect and then re-connect almost immediately. Usually occurs when I first wake the system but, it has also occurred randomly as well.

Tony

JANSJE

Level 1

0 points

Mar 4, 2011 2:25 AM in response to Tank9

Thank you for your answer. I knew that my problems with the 3 years old MacBook Pro have nothing to do with the unexpected shut downs. I use Macs myself since 1989 and since that time I had no problems until 2011. I wanted to tell everybody that I am a little disappointed about my Macs. I have a G5 of 8 years old and it still works. I cannot throw him away because I have an Apple LaserWriter 8500 and a HP LaserJet 4MV (very old) and so I can print via the G5. My brother (very technical) thinks that he has a new solution for printing via my MacBook Pro and the new iMac 27". Apple does not support these printers anymore... I cross my fingers!

Satoneko

Level 1

15 points

Mar 5, 2011 4:12 PM in response to JANSJE

@JANSJE

Your situation sounds so much like mine. I took my iMac in for repair, they kept it for three weeks and replaced the power supply unit but the problem never resolved. I saw the threads about the RAM problem, but being a "sensible" person, I didn’t “believe everything they say on the Internet.” I trusted my repair techs, I sent the iMac in for repair again, they changed the PSU again, but that didn’t solve the problem. Well, in my case, all the buzz on the Net was correct.

I am sure that some of the shutdowns are caused by problems other than RAMs. In fact, there was a relatively recent thread here where the poster found that the external device was causing the shutdowns. It takes some trial-and-error to figure out. Please keep us updated on how things go with you.

Also I agree with you that the new Macs seem to have a lot of problems. I bought my first Mac in 1991. It was an IIfx and it lasted 10 years. I had to retire it because it was so old, but it ran perfectly on System 7 until its last day. I hope to get at least four years out of my current iMac.

JANSJE

Level 1

0 points

Mar 7, 2011 10:08 AM in response to Satoneko

Hi Satoneko, It is too early to cheer or shout it out. So far no unexpected shut downs. Anyway, I keep you informed about it. I bought another two years of guarantee for the security.

JANSJE

Level 1

0 points

Mar 9, 2011 9:52 AM in response to JANSJE

Hi Satoneko/Peterwillem, I have very bad news. My iMac (5 weeks in repair by iCentre (official Apple repair centre), shut down to-day when I was scrolling in Safari (this happened two months ago also in Sarari now and then. I am very frustrated and desperate: I cannot miss my iMac for another five weeks and must work on my old G5 computer (old programs) or MacBook Pro (too small for an A4-page.

Mar 9, 2011 2:26 PM in response to JANSJE

Well as I suggested before : try reducing the ram. If you have the original 2 x 2 G Apple ram that came with your iMac and put 2 x 4 G Mushkin ram into your iMac. How to do it is shown in the little apple manual that cam with your iMac. It is really easy. You must have however a proper tool, a screw driver that fits the little screws in the backplate of your iMac.
Working with 2 x2 plus 2 x 4 G ram = 12 G is enough for most normal tasks.( except maybe for extensive photo/video editing)
If that ( the 12 G or maybe 8 G if you bought 16 G mushkin from the start) still causes shut downs, I have some 8 G OWC ram for you. OWC ram works, for me at least, as long as you do not use 16 G of it. We live in the same country ,so it would not be much of a problem to make some arrangement.
suc6

peterwilem

Mar 9, 2011 8:32 PM in response to Benjamin Running

Benjamin Running wrote:
I upgraded my 27" i7 with 2x4GB DIMMs from Crucial.com soon after the release of the machine and I was having the shutdown problem.

I contacted Crucial to see if they were aware of the problem.

They told me that the chipset had been updated, issued me an RMA, and I've been using the new DIMMs for about two weeks now with no shutdowns. I'm not ready to say it's been solved for sure, but so far, so good!

well, i spoke too soon.

gave the machine some heavy use this evening, CS5 apps, lightroom 2, and had a random shutdown just now.

back to the drawing board.

Tank9

Level 1

0 points

Mar 10, 2011 12:48 AM in response to peterwillem

It's been a week now since I downgraded to 12gb and there has been no shut downs. I am still waiting for Mushkin support to get back to me.

Mar 10, 2011 1:24 AM in response to Tank9

Ok, I expect you will have no more shutdowns. I don't think Mushkin will come up with a solution, so you better ask for a refund.
If you really need 16 G ram for work or otherwise so can try Samsung factory original ram, but that is not a 100% guarantee.
Apple has to come with a solution but I very much doubt they ever will.
Likely the new generation iMac will be suitable for all kinds of 16G ram. Unless of course they have some marketing strategy to make the iMacs only suitable for their own expensive kind of ram ?
But that is evil thinking!

peterwillem

JANSJE

Level 1

0 points

Mar 10, 2011 10:51 AM in response to peterwillem

Hi boys, Today I could not work on the iMac. In Photoshop I copied and pasted a photo into another file and the iMac shut down (5 times after new trials). I had to work on my MacBook Pro. I complained by the dealer and the Repair iCentre. I now get 2 x 4 MB original Apple RAM and (my brother has to do it for me, I am a dummy) he has to get out 2 x 4 KINGSTON RAM. If I get shut downs again, I get a new iMac.
You 'll hear the results from me...

JANSJE

Level 1

0 points

Mar 10, 2011 10:56 AM in response to JANSJE

Sorry, I get 2 x 2 GB APPLE RAM and 2 x 4 KINGSTON RAM has to stay, so I have in total 12 GB RAM.

Satoneko

Level 1

15 points

Mar 10, 2011 12:42 PM in response to JANSJE

@JANSJE
I hope reducing the RAM will work for you. I really sympathize with you because my situation was very, very similar to yours. While my 27” was in repair or too unstable for work, I had to use my C2D 17”, and it felt like I moved from a 5-bedroom house to a studio apartment with all the furniture. When you get used to working with 27” monitor, the small screen is just too small!

@peterwillem
No, I don’t think Apple is doing this on purpose. I think it’s some design fail in the Mac that is intolerant of the slight difference in RAM configuration and in the RAMs that aren’t configured exactly according to the specifications. But I do wonder why it happens in some machines but not in others. Perhaps there is difference by lots? I do agree with you that this problem is likely to get fixed on the new iMacs, but don’t think the exact reason why it happened in the 2010 iMacs will be ever disclosed.

Mar 11, 2011 8:30 PM in response to Anthony Godin

So, my second random shutdown occurred tonight - just past a week from the first time. I've decided to remove one of the 4 x 4GB Mushkin ram modules. So, I'm down to 12GB which everyone seems to indicate is the magic number for non-oem memory modules to work without issue.

Again, I'll keep this thread updated as to whether this successfully solves the issue for my 27" iMac Core i7 system.

Regards,

Tony

Mar 12, 2011 12:44 AM in response to Anthony Godin

Better is to remove 2 x 4 G modules and replace them with the 2 x 2 G Apple original modules.
I believe that a bank should be filled with complete slots.
See this site: http://www.computermemoryupgrade.net/maximum-standard-memory-slots.html

peterwillem

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27-inch / 27" iMac Random Shut down