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

Mar 27, 2011 12:04 PM in response to Berry with an A

Hey All,

Apple finally replaced my 27" i7, and believe it or not, the same thing happens with the replacement.

I just got put on the phone with one **** of an investigator from apple, who had me email him my error logs.

He noticed that every time the the computer shuts down after it goes to sleep, there's an error message involving something plugged into a usb port. We've got a wacom tablet, external hard drive, printer, and usb hub plugged into the computer. The usb hub just has a scanner plugged into it.

I think he's onto something, since the computer didn't have any problems for a few days when we first got it, and we with out all the extras plugged in.

I'll be in contact with him tonight, to let him no whether or not another random shutdown has occurred.

Mar 27, 2011 2:04 PM in response to brianmccarthy

We removed all USB devices from the chain because the first time we had it in for repair, they were trying to blame it on the Wacom. I deinstalled the Wacom driver and unplugged it and was still able to reproduce the issue. So I do not think it is related to USB devices. The fact that I am able to eliminate this issue from Photoshop by changing the tile cache size tells me that it is an issue with memory and the problem would be in the memory controller on the motherboard.
How do we get enough attention to this problem to make Apple take notice?

JANSJE

Level 1

0 points

Mar 30, 2011 7:42 AM in response to peterwillem

Peterwillem and Satoneko and other owners of an iMac 27" with 16 RAM with problems...
I am a late believer, but since 14 days, my iMac 27" i5 - 16 GB RAM/and now 12 GB RAM

- I had no shut downs anymore. My computer came with 16 GB RAM (4 x 4 0x80CE, not KINGSTON as I wrote before). I got from my dealer 2 x 2 GB RAM 0x80CE and my brother replaced this RAM and removed 2 x 4 GB RAM. A friend of mine bought his computer by Apple Online and his computer came also with 4 x 2 0x80CE RAM and has no problems. Maybe in the Netherlands this is the original Apple RAM?
I can say that my random shut downs came by using the Photoshop transformation tools 8 times after each other (so I had to use my MacBook Pro for this), 3 times after each other by starting the machine, by scrolling in Safari etc. Don't go to a repair centre, because it does not help and my Adobe letterfonts and fontexplorer did not work well, I could not find my printers etc. The iMac was 5 weeks by the repair centre and it did not help! I keep in touch with you and I hope with good news!

Jeff Donald

Level 8

44,790 points

Mar 30, 2011 10:10 AM in response to JANSJE

Sounds like a Photoshop issue rather than a hardware issue. Have you updated to the latest version of CS5, 12.0.2? Have you adjusted the tile size to 1028K? Title size is a known issue for causing severe slow downs of PS.

Message was edited by: Jeff Donald

Mar 30, 2011 10:28 AM in response to Jeff Donald

Not specifically a Photoshop issue but rather something about the operations that Photoshop performs causes the shutdown to occur. We had the issue in the latest version of Photoshop CS4, 12.0 of CS5 and 12.0.2 of CS5. So it is not specific to Photoshop. Just happens that we are in PS a lot and so it shows up more often. Specifically the transform operation seems to trigger it more than anything.
I'm going to post over on the Adobe forums to see if I can get some technical explanation as to what is happening behind the scenes of Photoshop when a transform occurs. Such as how much is handled in memory, exchanged as swap, exchanged between RAM and video RAM, etc. Even if Photoshop isn't the cause of it, perhaps it can help to draw out the main issue that is at fault.
Think of Photoshop not as the cause, but as something that can stimulate or irritate the symptom of a cause.

Jeff Donald

Level 8

44,790 points

Mar 30, 2011 10:35 AM in response to Scott Griswold

I teach photography at the college level and have been following your posts for the last couple of days and couldn't get a crash using PS CS5. I use 16Gb of OWC ram, not Samsung. I could cause a severe slow down of CS5 by switching Title size to 128Kb. But I could not get a crash. Use of small tile sizes is a known issue and reported on several Mac performance sites.

Mar 30, 2011 10:51 AM in response to Jeff Donald

We fixed our issue with OWC RAM, so I would not expect you to see the issue. It happened with ram from a different vendor called "Lifetime Memory Products". I can't help but wonder if there is an issue with the way some RAM exchanges info with the Video RAM in order to speed performance in terms of redraw. I'm not technical enough to know how exactly that happens or if it happens, but it always seems that the problem occurs not during the heavy processing of an image, but during a drag operation, window scroll, or image redraw during a resize. All things that the video card plays into.

ChrisCox

Level 1

20 points

Mar 30, 2011 10:55 AM in response to Scott Griswold

You are definitely describing a hardware problem, probably in the RAM, but possibly in the motherboard. (having inadequate power supply to the RAM is a common problem that causes this - could be a bad capacitor, or a bad MB design)

An Apple technician should be able to put a scope on the power and signal pins of the RAM and see the problem happen -- they should be looking for a capacitive discharge pattern in the signals, dropping below signal threshold, which will then trigger a system safety shutdown as if the power supply had failed. And since you've identified Photoshop as an easy way to reproduce the problem - now the Apple technicians should be able to find the cause and get your system repaired.

Mar 30, 2011 11:09 AM in response to ChrisCox

Thanks Chris, Good information. I'm going to link back to the Adobe Discussion for others to see yours or anyone else's additional comments. Much appreciated.

http://forums.adobe.com/message/3583201#3583201

Jeff Donald

Level 8

44,790 points

Mar 30, 2011 11:16 AM in response to Scott Griswold

Again, sounds like cheap, substandard ram that really doesn't meet Apple specs. The fix isn't on Apple's part, but rather the end user that needs to buy better ram. Of course the consumer has no way of knowing the specs, other than what a website or manufacture states as "fact".

Apple has a standard for ram, manufactures must meet the standard in actual performance, not just printed specs. Consumers have no way of knowing if the ram they purchase meets the specs or not, except by installing it and using it. It's now pretty obvious that a lot of the ram is not meeting Apple's specifications and consumers should be using the recent OWC brand and Samsung ram. Use of other brand ram will lead to problems.

Jeff Donald

Level 8

44,790 points

Mar 30, 2011 11:21 AM in response to ChrisCox

Apple technicians do not use scopes and diagnosis repairs to the board level not the component level. The trouble shooting guides lead the geniuses to the board and they replace the component and then test for a period of time to see if the fault can be duplicated or not. AASP may use other methods.

ChrisCox

Level 1

20 points

Mar 30, 2011 11:59 AM in response to Jeff Donald

Apple technicians do not use scopes and diagnosis repairs to the board level not the component level.

That depends, are you talking about the ones at the store, or the ones in regional repair centers and Cupertino? I know for a fact that Apple does have technicians and engineers quite proficient in using storage scopes and finding problems like this. They're just not in the stores.

ChrisCox

Level 1

20 points

Mar 30, 2011 12:04 PM in response to Jeff Donald

Again, sounds like cheap, substandard ram that really doesn't meet Apple specs.

You mean that the RAM doesn't meet the JEDEC standard which Apple supports?
Or that Apple's implementation of the RAM interface doesn't meet the requirements of the JEDEC standard that the RAM was tested against?

Apple implements a standard (not determined by Apple).
RAM makers build and test to that standard.
There could be problems in the RAM meeting the standard, or in Apple supporting the standard.
You don't know which is the problem until you test the components.

Jeff Donald

Level 8

44,790 points

Mar 30, 2011 12:19 PM in response to ChrisCox

Engineers may/do use scopes, but Stores (hence my references to geniuses) and Depot (central repair) do not use scopes. A repair will not get to the engineers during a product cycle unless Apple specifically issues a request for the "capture" of those machine so that the issue can be diagnosed. At this point in the product cycle, engineers are not looking into these types of issues (in most cases). I can't speak in absolutes, just generalities, being a former Apple employee.

Jeff Donald

Level 8

44,790 points

Mar 30, 2011 12:38 PM in response to Jeff Donald

Apple doesn't implement standards, they just conform/observe standards. Samsung ram has worked in various configurations since product release, HUH! Other brands have issues with Apple hardware, but Samsung brand works fine.

OWC, a reseller, states in late December that they have "tweaked" their ram and now their OWC brand ram works in all various configurations. However, other brands of ram don't work and causes crashes. The empirical evidence suggest the ram is at fault and not the Apple hardware. Some software may cause crashes or stress the hardware enough to cause crashes as well. But the underlying cause is the ram from various brands that haven't been "tweaked," like Samsung or OWC.

So what is "tweaking" ram? Manufacturing ram to meet the actual specifications? How is ram manufactured cheaper? Do you cut corner, less rigid standards and inspections before shipping to resellers? Why does Samsung ram cost more? Huh, they have tighter tolerance, standards and don't ship product that meets minimum standard and hold themselves to the actual specs?

Message was edited by: Jeff Donald

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27-inch / 27" iMac Random Shut down