Problem with 16GB on 2010 iMac 27" i5 & i7.

Thanks Jeff.C I did just that and OWC sent me an RMA, with a UPS prepaid postage to return the old batch. Once they receive it, they are going to send me a replacement with a newer batch. I must say I'm very impressed with OWC!
As soon as I receive the new ones, I'll post my results here..

Hi,

I got my new iMac i5 2.8 27 inch (mid 2010) in the post today. I had the RAM pre-ordered and ready to install. I got exactly the same RAM that comes in the iMac, as far as I understand.

The iMac came with 2 x 2 GB DIMMS and I bought 2 x 2GB DIMMS for a total of 8GB over 4 DIMMS.

The new RAM is HMT125S6BFR8C-H9N0 - 2GB Hynix DDR3 SO-DIMM (PC Notebook), PC3-10600 (1333MHz), 204 Pin, Unbuffered.

Once it was installed, it just didn't even show up that I had installed it. Is anybody else getting that?

Billy

The shop (Macnificos, Spain) where I bought 4 modules of 4 GB of Ram that causes random shutdowns on my iMac 27, has been in contact with the distributor and manufacturer of CSX Ram because some other clients experienced the same problem.

They affirm that shutdown problem is an electric problem of iMac, not a problem of Ram modules, and they are sure that can ocurr when the machine has 16 GB of Ram installed and with some specific modules. CSX can't found any problem on their modules, so they think their RAM is OK, and assure that the problem is random and also can ocurr with Samsung RAM. They think perhaps my modules are defective. I'm not agree with this explanation.

They accept to change my four 4GB modules of CSX RAM with four new identical modules. I will try it all next week, and I will warn you if the problems persist with the new modules, but I'm sure that shutdowns will be continued ocurring because the modules that they're sending to me are identical to that already I have.

Received today 4 new modules of 4 GB CSX RAM. Same problem, after installing, random shutdowns.

So, no defective RAM, sure incompatibility Issues.

With 12 GB, 8 GB (2 modules) or 4 GB (1 module) no problem. With 16 GB, impossible to work.

Waiting a response from the shop for the possibility to change this RAM and get Samsung which does not produce shutdowns according to report several users.

I've also tried Micron (Crucial) RAM at first – mixed with the Apple RAM, but the iMac crashed on wake up. Now I bought another Crucial Kit with 8 GB and installed 16 GB from Crucial. And it works. In between I found out that I did the wrong order of 1333 MHz RAM for my older 1067 MHz iMac.

I could return my actually working RAM to Crucial and because they were now out of stock with 1067 MHzs, I bought the right 1067 MHz RAM from Hynix (because I don't like the association of Samsung with the military sector).

Now the *16 GB Hynix RAM works fine* and … I couldn't be happier. As stated before latency and clock speed are important!

Let me confirm as well that Hynix RAM apparently works fine.
I've made the mistake to order my machine including 8GB RAM from factory.
Was lucky enough though that the extra 8GB RAM I bought (unaware at the time) matches the part numbers of the original ones to the last digit.
I then became aware of (and quite frightened by) this thread, but I've had the machine running for over 10 days now and (knocking on wood) encountered no problems whatsoever so far.

Can you post the model/part numbers of your flawless 16 GB of Hynix please.

I have been having cut out/crash issues with 16gb of OCZ (model/part number: ocz3m13338gk). Having the factory 4GB (Samsung) and 2 of my 4 4gb sodims and the machine is fine, install 16gb and actually use it (Logic or Photoshop) and 'bink' gone.

Never thought anything of buying OCZ ram for my mac, pretty much always used it in my PC builds and have had OCZ in my MBP for nearly 4 years without a hitch!

After reading this post, the OCZ is going up for sale and am replacing with Hynix or Samsung.

Sure!

System Profiler says:

Manufacturer: 0x80AD
Part Number: 0x484D54333531533641465238432D48392020

don't suppose you can tell us which 5 sets they were and if you ever got a magic 16 gb.

ooo and if you did get a magic 16 what is it?

Cheers

Thank you, erm, I just can't anything with those details from your system profiler. Its the cl rating and the voltage i'm after really. from some research i've done the voltages can play havoc with i7 imacs. some so-dimms are operating at 1.5v and others at 1.3v (i think i remember that right).

Thanks again

Message was edited by: DJ Nasty Fingers

They're CL9, PC3-10600 1333Mhz.
Manufacturer's Part Number is: HMT351S6AFR8C-H9
Apparently, 1.5V, according to the data sheet.

Hope that helps.

Message was edited by: Tozzi

Thank you very much Tozzi.

For everyone still having problems, I'm going to try 2 x 4gb OCZ and 2 x 4gb Hynix see if that causes issues.

Will post results when I have them.

I cannot believe that .2 ms in response times causes so much hassle!

Hi to everyone,

we are a leader provider of memory for Apple systems in Europe and authorized distributor of Samsung original modules. I would like to confirm that according to our tests and to the feedback of our customers, a set of 4 x 4 GB Samsung original modules work flawlessly and don’t show the problem that you encountered on your 27” iMac. Samsung original modules can be purchased from us through all Apple dealers in Europe, Africa and Middle East.

Marketing Team - ICEBERG Technology

PS: I may receive some form of compensation, financial or otherwise, from my recommendation or link.

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 use 16gb Mushkin Enhanced ram on programs like Adobe Premier Pro and it crashes at least once in 8 hours, and more often while using Maya 2011. The ram passes all test using memtest4.22. Crashes is not as often and somewhat tolerable, but I'm still not too happy about it.