27-inch / 27" iMac Random Shut down

So this seems to have resolved the issue for me as well.

My system (27" Mid 2010) never really shutdown or panic. I would just get GPU dropping into Debug mode in the log. after which the Mouse and Keyboard would stop responding and I would have to ssh in and run shutdown or power the unit off.

I had tried smcFanControl with no luck in stopping the issue, although it did run cooler..

The part I don't really understand is the 16GB lets call them 8GBA and 8GBB when all installed causes the issue. When running 12GB with 4GB and 8GBA it works fine, or when running 4GB with the second set 8GBB it works fine. To me this implies that there is really no problem with either of these sets of memory.

Implies to me either to be a problem with LION and 16GB on this mother board combination or ?

either way 12GB configuration works.. go figure.

Hi guys,

Fascinating post,

Unfortunately my Imac also seem to have developed the random shut down problem .

Mid 2010 27inch i5 2.8 quad,OS X 10.6.8. 12GB ram. Bought in April last year, came with 4GB Ram, bought 8GB Ram from Crucial (always reliable in the past) & being having random shutdowns ever-since.

Imacs currently with Apple, I wanted to get the hardware checked out first before I start playing with different ram manufactures.

Surly Apple must know what problems lie within its shiny shiny box of tricks. As with many peoples posts on this forum, I've been scouring through console logs trying to figure out what may be causing the problems... but concluded that i don't have the technical know how to figure it out. I can replicate the shutdown using Photoshop CS5, but issue has also happen during browsing using Firefox, Safari and Mail.

Hope Apple pull out a magic fix solution soon as its infuriating & starting to cost me money.

Andy_gib,

Much as I applaud your desire to wait for a magic fix, I think you'll find much more productivity in simply replacing the RAM. I had Crucial memory as well (which ironically I selected because I wanted to pay more for 'the best'), and replaced it with OWC ram and have had ZERO shutdowns since then, which has been more than 6 months (after having loads of shutdowns for the 4 months before then).

If you make money from having your computer working, you'll make back the ~$100 (or less by now) for the new ram and just chalk it up to cost of business.

Cheers Matt,

Ordered two sticks of 4GB Samsung memory.

Picking up imac from store tomorrow..... will install & see how it goes.

I have a Mid-2010 model 27" iMac i7 and experiencing the same issue with 16GB Crucial RAM. After removing one stick, the machine does not suddenly turn off, works fine. Just sharing... ... another victim.

The RAM passed a Rember test. Getting an RMA (replacement) from Crucial, but I don't think that the RAM is the problem. Seems like a firmware issue. Crucial has been very helpful during this process.

So, any updates on running with 16GB?

@Paul G., I'm still having the same issue as you on my iMac. I still don't have the time to drop the iMac off at a place, so I've been trying things here.

I convinced Apple to send me new RAM to try (knowing there was less than a 5% chance of success). And you guessed it... same problem.

Next I installed a clean OSX 7.0.2 on an external drive and ran that for a day. It runs fine. So, I'm thinking I have a software or driver issue. If I boot into Safe Mode it seems to run fine as well.

So I've been uninstalling all sorts of apps (things I don't need mostly... and things that I used in Snow Leopard that aren't officially supported in Lion), but still have no luck.

I'm about to give up and just do a fresh install. I wish I could track down the bug or driver, but I just don't know how (I love the command prompt and am in it daily, but am by no means an expert).

iMac 27inch, i7, 16 Gb ram.

I am having the random shutdown problems also.

I did put in some new Ram earlier in the year.

Interestingly it doesn't seem to shutdown on my admin account, just other user accounts.

I am running the latest OS X, never seemed to do this before that install earlier in the year.

I am going to phone apple and at least get on some list...since I have warranty still.

I too am having the shut down phenomenon. I did increase my memory a couple weeks ago with Crucial brand memory, and thought that was the problem, but I have triple checked my connections with the memory, and they are secure. I will try to reset my SMC, and then maybe this week reinstall the old memory to see if that fixes it. I run iMac 27", 2.8 i7, 16GB 1067MHz DDR3, 2TB HDD, Lion 10.7.3. Peripherals attached: EyeTV Hybrid, Bose 5 system, FW800 HD, Canon Scanner.

Update: I struggled with this problem for a good few months, using 12gb not 16gb.

Got imac checked over by apple, came back clean without problem. Got it home fired it up same thing happened …random shutdowns. I took advice off this forum and swapped Crucial memory for Samsung early January. No problems since. Crucial were great, full refund. I believe its a know problem at Crucial which apparently has now been rectified??

Well..glad it worked out for you.

I guess I will go check what ram I have and if applicable attend to it.

Though I don't have a lot of time for diddling around with computer stuff atm.

regards

I don't think Crucial memory is the problem at all, in fact, I don't think. 12GB is the solution either.

I have an 11,3 iMac i7 that came with 4 GB Hynix memory, to which I added 2x4GB crucial memory last January.

It was running fine until the lion update 10.7.2. I started seeing the shutdown problem, but didn't recognize it until a couple times. I had checked console and saw nothing.

I ordered two weeks ago, a 2x8GB Komputer Bay kit from that online store everyone knows and installed it, keeping the crucial 4GB chips, but all ram being reseated.

For two weeks now, no problems with shutdowns, it has 2x4GB and 2x8 GB for 24 GB total RAM.

No more shutdowns. still have the crucial memory, but got rid of the apple Hynix factory chips.

My theory is that the firmware got corrupt around the time of 10.7.2 in a way that made it unstable to have the same memory installed... And I bet, but I'm not going to try, that if I reinstalled the apple memory and crucial memory in the same configuration as it was prior to my memory upgrade, the shutdown would start again... Just a theory, though.

Now, the latest iTunes has caused two kernel panics, but that was all traced right to iTunes and I sent those reports to apple.

I got an approval from Crucial to send them the memory back and get a replacement, but have stalled on sending it back. In fact, gotta send it back soon, or the approval will expire. I agree with you and suspect that there is a firmware problem... so sending it back seems silly.

Apple pushed a firmware update recently, but did not mention this issue. Before sending the RAM back, I want to use it one more time, but running perfectly fine with one stick removed (12GB).

Paul G. wrote:

I got an approval from Crucial to send them the memory back and get a replacement, but have stalled on sending it back. In fact, gotta send it back soon, or the approval will expire. I agree with you and suspect that there is a firmware problem... so sending it back seems silly.

Apple pushed a firmware update recently, but did not mention this issue. Before sending the RAM back, I want to use it one more time, but running perfectly fine with one stick removed (12GB).

Same here Paul. 12-14 GB have worked fine. Can't confirm the firmware idea. Can confirm that 16GB cause shutdowns.

Ivan Robertovich wrote:

I don't think Crucial memory is the problem at all, in fact, I don't think. 12GB is the solution either.

I have an 11,3 iMac i7 that came with 4 GB Hynix memory, to which I added 2x4GB crucial memory last January.

It was running fine until the lion update 10.7.2. I started seeing the shutdown problem, but didn't recognize it until a couple times. I had checked console and saw nothing.

I ordered two weeks ago, a 2x8GB Komputer Bay kit from that online store everyone knows and installed it, keeping the crucial 4GB chips, but all ram being reseated.

For two weeks now, no problems with shutdowns, it has 2x4GB and 2x8 GB for 24 GB total RAM.

No more shutdowns. still have the crucial memory, but got rid of the apple Hynix factory chips.

My theory is that the firmware got corrupt around the time of 10.7.2 in a way that made it unstable to have the same memory installed... And I bet, but I'm not going to try, that if I reinstalled the apple memory and crucial memory in the same configuration as it was prior to my memory upgrade, the shutdown would start again... Just a theory, though.

Now, the latest iTunes has caused two kernel panics, but that was all traced right to iTunes and I sent those reports to apple.

I don't think the RAM is the issue either. It can be though in these cases. Many have eliminated that as the potential cause. I and several otehrs can confirm that 12-14 GB have worked fine. Can confirm that 16GB causes shutdownsCan't confirm the firmware idea, although it could be a possibility.. My iMac is maxes out at 16GB, so I cannot relate to the 24GB setup.