27-inch / 27" iMac Random Shut down

As I've explained some weeks ago, I experienced random shutdowns with my new 2010 iMac 27" 2,8 GHZ when I upgraded it to 16 GB of Ram with 4 modules CSX sold by Macnificos.com (Spain).

This shutdowns happened many times when I was surfing the Web. Most of them happened when I visited Marca.com with Firefox, but surely the system could have shutdown while I was carrying out any other task.

There was no shutdowns when I downgraded the iMac to a 4 GB, 8 GB or 12 GB configurations with the same modules. The iMac shutdowns happened only when it was 16 GB.

After installing 4 new CSX modules the last week, my machine continued shutdown randomly.

Finally, I've received 4 new 4GB Samsung modules to replace the CSX RAM this friday, and I haven't experienced more shutdowns since I installed them.



My conlusions are:

1) Only Samsung modules can be used safely to configure the new 2010 iMac 27" with 16 GB of Ram, although modules from other manufacturers can work in certain specific equipment or for some users, but not all.

2) Similar problems on other models of iMac (iMac 24", iMacs from 2009) can don't be related to a Ram problem. The shutdowns happened on this other machines with the same symptoms can be produced by another problem.

3) In many cases, it's possible to use RAM from manufacturers as Kinston, Hynix, CSX, Corsair or OWC in the iMac 27" 2010 but only with configurations with a maximum of 4 GB, 8 GB or 12 GB. With 16 GB configurations, the modules of all this manufacturers can produce or not random shutdowns, althought the modules are provided by Apple when we bought the machine. Apple includes different manufacturer RAM to their iMacs, but probably only those suministrated with Samsung modules can work with 16 GB without shutdowns.

4) Of course, PRAM reset, SMC reset, completly Mac Os reinstall and other similar procedures doesn't solve the problem.

5) Apple don't know how to solve or fix this. Apple support offers changes of power supply, motherboard or complete machine, but no one of these steps solves the problem.

6) Apple isn't informing about this RAM problem, and their users and clients are completely disinformed. Everytime the problem appears on a new machine, its user has to spend a lot of time, perhaps sending its equipment to repair without satisfactory results, until he found the solution explained on this forum.

7) One more time, Apple is not behaving as we would wish. They would have to mention the problem to new buyers or at least to its technical support services so that they do not replace equipment, power supplies and other components without purposes. They would have to propose directly a change of ram memory to Samsung modules while their engineers investigate the problem and find a definitive solution.

8) If you are experiencing this problem, the only solution today is use Samsung RAM or configure the machine with less than 16 GB.



In order to finish, I want to be thankful to Macnificos.com by its amiability and help to fix my problem. They acceded to change my 4 modules of CSX for 4 modules of Samsung and now I can work without problems.

I just want to add a different ram brand that nobody has yet mentioned and is specifically sold for apple iMacs, "Mushkin."

I bought two of the following:
Mushkin Enhanced 8GB (2 x 4GB) 204-Pin DDR3 SO-DIMM DDR3 1333 (PC3 10666) Dual Channel Kit Laptop Memory Model 996647

* DDR3 1333 (PC3 10666)
* Cas Latency 9
* 1.5V

My iMac has turned off randomly while working on Premiere CS5, Maya, After Effects, and while watching a movie on VLC player.

Thanks for this fine post. I have just read the past three months' post on this topic, because my new 27" iMac lasted all of 20 minutes before it shut down today. In my case, I can't get it started again. It's the same as if there were no power supply. Does this sound like part of the same problem, or a different one?

My iMac came with 16GB of RAM, specified only as "Expercom", the re-seller's name. I'm reasonably sure it's not Samsung.

I was going through the initial set-up and migrating files from my old Mac when the new iMac shut down. I only mention this to emphasize that I did not run across in these posts any which experienced a shut down so quickly and, apparently, permanently.

Well I think it is a different problem. Because in most cases written about before in this thread and the many others in this forum the shutdown did not happen so fast after the first start of the iMac.
And ,as far as I know, you could always start the iMac again after pressing the power button behind.
Advise to go back to your reseller asap.


peterwillem

There seems to be people having problems with RAM. If you buy RAM upgrade for your iMac then obviously check everything is seated corrected, you need to give the RAM a good hard push so its seated correctly, yes you will get sore fingers! lol, once your RAM is installed select about this Mac once booted up and make sure it tells you you have the correct amount installed.
If everything seems fine and you still get the shutdowns then remove the newly installed RAM

Purchased my 27" iMac Jan/2011 year from a Dealer (Hard und Software Blüm) in Germany (I am German) and have had the random shut down problem almost from day one after first Power On.
My dealer is NOT interested in solving the problem. :-((
I do NOT know which RAM is inside, only 16 GB i know ...

Is it a Problem which fix with a FW or OS Update from Apple ?
Did anybody have a DIRECT (Apple) Support E-Mail Adress zu tell/describe THIS problem ?

*!!! Apple please FIX this blameful Bug *

Message was edited by: EKOisGPSy

Hi,

it doesn't seem that apple would release an update fix for this, why would they? it doesn't seem to be the OEM RAM causing issues?

Anyway you say you have 16G RAM, is this 16G straight from apple or installed elsewhere?

I do not know...., my Dealer 😟 send the iMac with 16 GB. Which manufacturer = ???

Ok, i am beginning to get a picture here of people having problems with using an iMac with the full 16G RAM! unless its the samsung OEM type,

1 thing you could try if you are ok with removing RAM? Please dont if you are not!

Remove 2 sticks of the RAM and leave your iMac with 8G, i assume you have 4x4G installed?

Try that, if no shutdown then there is indeed some sort of issue here!

Before you remove RAM touch the iMac case to make sure you are grounded!!

I just spoke with someone from Apple Support Express Lane who agrees with peterwillem about my iMac: the one that shut down yesterday during the initial set-up after only 20 minutes, and cannot be restarted at all.

The Apple guy said that I got a dud, and I should return it to the re-seller and get a replacement. And not settle for having this one repaired, because I would lose time on my warranty.

After reading this thread, I now have an opportunity to avoid the grief others have had.

I like ChoPraTs' advice in this thread to "use Samsung RAM or configure the machine with less than 16 GB" because I want this machine and I want it to work! But maybe getting any configuration of this model is only asking for trouble?

I am using an iMac 27" i7 with 8G RAM, 2 sticks are OEM and 2 sticks I purchased myself, I have been using this for video editing and some gaming and music, not one single shut down or error or anything else, it works perfect. I have yet to come across an app where I feel I need to increase my RAM so can't comment on the 16G problems, all I know is you do not and never will need to use OEM RAM, it could be maxing it out has problems but then that's down to apple

Very interesting to read your issue. I am having the exact same issue with a brand new i7. Mine has went "DEAD" at random two times in two weeks. How concerned should I be. The Apple Tech was not near as concerned as I was, but he did not pay $3,000 + for an iMac that is supposed to be the top of the line.

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!

Hi

I have the same 2.93 Quad Core. Its one week old (this is lat Feb 2011). I upgraded the RAM to 16 GB and it shuts down randomly - similar patters as others have observed. I bought the 16 GB at Fry's and the guy assured me it was the actual brand Apple uses. He lied. When I removed the 2x2 I had they are Samsung. I just switched it to the 12 GB (2x2 samsung, 2x4 Corsair) and hope this stops the random off's. Its 2 to 3 times a day for me.

So to the person who posted the excellent and detailed description of this problem and suggested Samsung a big THANKS - I think you nailed this problem for this model.

TO APPLE - this is EXTRAORDINARILY frustrating - you should do better. Inform your patrons of the exact memory to buy. This has been going on for some time. You should have the decency to specify exactly which ram we can buy. Nobody wants to buy your ram in the store as it is ridiculously expensive. We all love your products. Either drop your in store prices or say, very clearly, exactly which make and models of RAM will work in the case of 16 GB. PLEASE TREAT US WITH MORE RESPECT!!

There are excellent posts here and I appreciate the info.

Glad you got it sorted geo_head, this seems to be a complex program, from the research i have done and from what others say if you where to use your non OEM brand ram but not take it to 16G then it would work fine, thus leaving the conclusion its not the actual RAM thats faulty, maxing the RAM at 16G without OEM seems to cause problems.