Level 1

3 points

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

I've 8 X 4GB 1333Mhz DDR3 RAM, latest 2010 iMac i5 & i7.
Trying to install 16GB on each iMac.

1. Both work well with 2X2GB.
2. After installing 4 X 4GB RAM , they freeze, cursor spinning ball or kernel panic within 10 to 15mins.
3. Removed all RAMs & installed another batch of 4X4GB, same problem.
4. Installed 2 X 4GB RAMs, they work well.
5. Repeat step 4 with the rest of the 6 pieces of 4GB, they work well with 8GB.
6. Also tested with 4 X 2GB, they work well.

I can only conclude that the new 2010 iMac 27" does not support 16GB well. No doubt it recognizes 16GB at "About This Mac" but it freezes after 15mins. I suspect is due the firmware issue.

Anyone else have the same issue?

Found similar problem at http://discussions.apple.com/thread.jspa?threadID=2567543&tstart=15

MacBook Pro, Mac OS X (10.6.4), iMac

Posted on Sep 4, 2010 3:13 AM

125 replies

myror

Level 1

0 points

Sep 21, 2010 6:38 PM in response to mcsys

I ran the extended hardware test, and everything came back good. Apple also suggested that I do a fresh installation. So I formatted the drive, and installed fresh. It was good for about 6 hours and just did it again. I'm downgrading to 12 now, but if I can't run 16 gigs in this like it is advertised to be able to.. its probably going to go back.

I'll Post my findings with 12 gigs installed.

labeck

Level 1

19 points

Sep 24, 2010 8:43 AM in response to mcsys

I've been through 5 sets of brand new 16gb kits and all have cause random shut downs on my 27" imac.

Its definitely an issue with Apple's firmware or software not liking when 16gb is installed. It takes 2-3 days for the issue to present itself but once it does it happens all the time. Apple needs to fix this.

mcsys Author

Level 1

3 points

Sep 24, 2010 10:56 AM in response to labeck

I just got another new iMac 27" i5 with Transcend 4 X 4GB RAM today.
It has been running fine for the past few hours. I shall leave the computer on for long hours overnight test.

None of the previous iMac 27" i5 & i7 installed with 16GB (generic brand) passed the test.

mcsys Author

Level 1

3 points

Sep 25, 2010 7:28 AM in response to mcsys

To date, the new iMac 27" i5 with 16GB Transcend RAM does not have kernel panic issue. no shut down or whatsoever.

Some RAMs information about 2010 iMac 27"
Apple Original 2GB RAM 1333Mhz
uses 8 X Hynix 1GB chip set on each side.
Printed on Hynix Chip
H5TQ1G83TFR
H9C 020A
MWJQ4317

Photos of Apple RAM
!http://farm5.static.flickr.com/4089/5023032038_e78c0247e9.jpg!
!http://farm5.static.flickr.com/4149/5022421743_8d45d5fe7b.jpg!

Transcend 4GB RAM 1333Mhz
uses 8 X Hynix 2GB chip set on each side
Printed on Hynix Chip
H5TQ2G83AFR
H9C 013A
MTJJ3K1591

Photos of Transcend RAM
!http://farm5.static.flickr.com/4090/5023030790_2b18ea8d01.jpg!
!http://farm5.static.flickr.com/4092/5022420547_dcb83a78a4.jpg!

mcsys Author

Level 1

3 points

Sep 29, 2010 8:34 PM in response to mcsys

After a month of troubleshooting, I finally solved my problem.

My first batch Strontium 8 X 4GB DDR3 1333Mhz RAMs are not fully compatible to install 16GB on iMac 2010. They work well with 8GB. But with 16GB, iMac shows kernel panic within 10-15 mins. I swapped RAM between 2 iMacs to find out the cause. The iMac 2010 simply could not take Strontium 16GB & eventually the iMacs were set to 8GB for 2 weeks without issue.

I got in another iMac i5 with Transcend 16GB & did a 24/7 test for 3 days without any issue. I transferred the Transcend 16GB to older iMac i5 & did the same test. Today is the third day & the old iMac i5 is still running perfectly with 16GB.

I can only conclude that iMac 2010 models are very sensitive & selective to some third party 16GB RAMs.

Sep 30, 2010 12:37 AM in response to mcsys

I agree with your final outcome of this issue.
But , for me, it does not solve the problem. I am stuck with 16 Gig of OWC ram, of which I can only use half.
RMA it to OWC and ask for refund will cost me a lot of extra money. (transport by Fed Ex= $130,- and vat and import duties another $130,-) .
Not to mention the buying of 20% more expensive Apple ram.
So I have to think about this if all that extra money is worth it, moreover because I really don't need all the 16 G of ram. For me it was more a matter of having, a expensive one as it turned out to be.
So for this moment I find it hardly except able that Companies like Apple and OWC put me into this spot in the first place. Both should do something about it. But I am realistic enough to realize that that will take a long time, if at all.

peterwillem

Sep 30, 2010 3:25 PM in response to mcsys

Thx,
I will look into that tomorrow. Meanwhile I have put 16 G of OWC ram in the iMac and within 7 hours I had the problem again.
I am trying one last option with the 16 G ram inside, and that is working OSX SL in the 64 bit mode.
That is supposed to make no difference but I want to make sure that that really is true.

peterwillem

Oct 1, 2010 8:24 AM in response to mcsys

As I expected the 64 bit mode did help either

quote: From the URLs, I see the RAMs are made of 4 chipsets on each side. I'm not sure whether that is the reason behind it.

Well the OWC rams I have are made of 8 chipsets each side, just like the Apple rams Hynix&Samsung.
So the 8 and 4 are not the cause of the problem, I would say.

I am going to discuss this with OWC and see if I can do some trade, but I want to be sure that the Samsung 16 GB will solve the problem.

peterwillem

peterwillem

mcsys Author

Level 1

3 points

Oct 1, 2010 9:58 AM in response to peterwillem

My problematic Strontium RAMs are also made of 8 Hynix chipsets each side. Probably is due to different circuit board that made the RAM.

May I suggest you install 3 X 4GB OWC RAM plus 1 X 2GB Apple RAM, total 14GB to see whether you get the same issue.

Oct 1, 2010 10:55 AM in response to mcsys

Well I have just a few hours ago installed 2 x 4 G of OWC ram and 2 x 2 G Apple ram.
So far no problems, but it is early days.
In one bank a 4G and a 2 G ram , will that work? Aside from the sudden shutdown issue.
I always thought that the rams in one bank should be equal in size.

Anyhow I will await the outcome of my present set up.

peter willem

Oct 1, 2010 11:13 AM in response to peterwillem

The RAM in the two top slots (closest to the screen) should match, and the RAM in the two bottom slots should match. The banks (as displayed in the System Profiler) correspond to right side and left side. It is confusing. I would put the Apple RAM in the top slots.
Probably the best design would be 2 rows of 3 banks for this chip. But they have probably figured out some other way to get three memory paths out of the banks.

Oct 1, 2010 3:25 PM in response to mcsys

I have sent a mail about this problem to OWC.I like to quote OWC reaction to my mail:

Hello,

+OWC has tested the ram in multiple iMacs of this group and the machines work fine with 16 gb of ram.+

XXXXXXXX
+Technical Customer Service Representative+
+Other World Computing, Inc. (OWC)+
+OWC.net, Inc.+

So how come that so many of us have problems with that same ram? What is going on?
Hope that somebody fromApple or OWC van shed some light on this.
I obviously X'ed the name of the person in the mail.
peter willem

mcsys Author

Level 1

3 points

Oct 2, 2010 2:52 AM in response to peterwillem

To proof that it works with 14GB, I deliberately downgraded my iMac11,3.

Photos tell a thousand of words

iMac11,3 "About this Mac"
!http://farm5.static.flickr.com/4092/5043341429_19986ded02.jpg!

iMac11,3 "Hardware Overview"
!http://farm5.static.flickr.com/4124/5043341531_d448742064.jpg!

iMac11,3 "Memory Slot"
!http://farm5.static.flickr.com/4146/5043341869_c553f7862a.jpg!

I'll test 14GB on iMac11,3 for 24hrs to see what happen. I think it should be ok.

Oct 2, 2010 3:50 AM in response to mcsys

Thanks mysys,
looks like you are right after all. But I have some questions. What type of ram did you use, transcend or strontium?
I am a bit confused with the banks and slots. Exactly where did you put the ram? If you put the iMac on its screen and open the ram compartment should I put the 2 x 4 G OWC ram in the upper slots and the 1 x 4 G OWC and the 1 x 2 G Apple ram in the lower slots? Or the other way around?
Or does it not matter?
If it works it is anyhow 2 G more in use.

peter willem

mcsys Author

Level 1

3 points

Oct 2, 2010 5:06 AM in response to peterwillem

I returned all Strontium RAMs back to vendor. I took another new 16GB Transcend RAM but these RAMs are made of Micron chipsets. My pervious Transcend RAMs are made of Hynix chipsets.

I placed 2 X 4GB on the slots away from the screen, 1 X 4GB on the slot near the screen & 1 X 2GB on the last slot (left or right doesn't matter).

Anyway, if user has only 2 pieces of RAM, he/she must install them to the slots away from the display otherwise the iMac will not start. Check the booklet "Everything Mac" that came with the iMac11,3 , see page 40 at point 8.

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