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

Question

Level 1

2 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

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Answer 1

den.thed

Level 10

82,234 points

Sep 4, 2010 7:03 AM in response to mcsys

Hello mcsys

Not all third party RAM works in an iMac, who is the manufacture and what are the full spec's?

Does that RAM meet all of these criteria?

PC3-8500
Unbuffered
Nonparity
204-pin
+1066 MHz+
+DDR3 SDRAM+

But as important, RAM with the following features *_will not work_* in an iMac's.

+Registers or buffers+
PLLs
ECC
Parity
+EDO RAM+

See > http://support.apple.com/kb/HT3918

Dennis

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Answer 2

mcsys Author

Level 1

2 points

Sep 4, 2010 8:05 AM in response to den.thed

Hi Dennis,

8GB (2X4GB) or (4X2GB) RAMs work well on both iMac i5 & i7. I've tested for a week.

The problem only occurred when I installed (4X4GB) 16GB to both set.

If those RAMs are not compatible, then the problem should appear on 8GB too.

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Answer 3

den.thed

Level 10

82,234 points

Sep 4, 2010 8:56 AM in response to mcsys

Why do you avoid the questions?

{quote:} who is the manufacture and what are the full spec's?{quote}

If it is not working together in sets of 4, then there is something wrong with the RAM and you need to contact the vendor for an exchange or return.

Maybe try OWC, there RAM is Mac tested:
http://eshop.macsales.com/shop/memory/iMac/2010/DDR321.527

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Answer 4

mcsys Author

Level 1

2 points

Sep 4, 2010 8:13 PM in response to den.thed

l'm not avoiding your questions but just lack of information. I forwarded the questions to my local vendor & now waiting for their reply.

I should check the link at http://support.apple.com/kb/HT4255 not HT3918
& the RAM criteria should be

PC3-10600
Unbuffered
Nonparity
204-pin
1333 Mhz
DDR3 SDRAM

For sure the RAMs are PC3-10600,204-pin 1333Mhz DDR3 SDRAM.
But I can't tell whether they are unbuffered & nonparty.

I knew about OWC memory but I can't convince myself that the new iMac 2010 will work with 16GB properly unless someone here tested it.

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Answer 5

den.thed

Level 10

82,234 points

Sep 4, 2010 10:43 PM in response to mcsys

You are correct! My bad, sorry for posting the criteria for the 2009 model instead of the 2010.

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Answer 6

Sep 8, 2010 11:45 PM in response to mcsys

Hi,

I'm having the same problem.

I have 2 x 8.0GB (2x4.0GB Kit) PC3-10600 DDR3 1333MHz SO-DIMM 204 Pin CL9 SO-DIMM Memory Upgrade Kit for Mid 2010 21.5" & 27" iMac Models from OWC.

I get the exact same issues, apple logo at boot then a hung spinner prior to the OS loading, one time the OS loaded and the about this mac showed 16GB, but after a varying number of minutes the same panic/crash.

I also get weird striping colours at boot time and various kernel panic errors.

I've gone through the same process, less memory no problem, but all four and a nightmare...

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Answer 7

mcsys Author

Level 1

2 points

Sep 10, 2010 11:34 PM in response to TheAnimist

TheAnimist got iMac 27" i7 with 16GB (RAM from OWC) having problem.
Why are you having 2 X 8GB?
I thought the RAMs suppose to be 4 X 4GB.?

To answer den.thed question.
Who is the manufacture and what are the full spec's?

Reply from my local vendor:
Generic brand.
RAM meets all criteria
PC3-10600
Unbuffered
Nonparity
204-pin
1333 MHz
DDR3 SDRAM

According to
http://discussions.apple.com/thread.jspa?threadID=2548180&tstart=150

Sjohnson803 got iMac 27" i7 2010 with 16GB (RAM from OWC) having problem.
Currently, RAM down to 12GB without problem.

Jeff.C got iMac 27" i7 2010 with 16GB (RAM from OWC) having problem.
Not sure his problem has solved.

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Answer 8

Sep 11, 2010 3:58 AM in response to mcsys

No, I've got 2 x 8.0GB (2x4.0GB Kit), so 2 8GB kits made up of 2 x 4GB, so in total 4 x 4GB...

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Answer 9

Sep 14, 2010 6:48 AM in response to TheAnimist

Just as a side note, this memory (the 16GB) has been running fine in my first iMac for over 3 wks, so the memory is good. All point to an internals problem

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Answer 10

mcsys Author

Level 1

2 points

Sep 20, 2010 8:12 AM in response to TheAnimist

Update…
Some data collected from
http://discussions.apple.com/thread.jspa?threadID=2548180&tstart=150

Most users solved their problem by downgrading the RAM to less than 16GB.

Having problem with 16GB on 2010 iMac 27", downgrade ok.
1. myself, mcsys - i5, i7, i7 8GB - OK
2. Sjohnson803 - i7 12GB - OK
3. Jeff.C - i7 8GB - OK
4. TheAnimist - i7 8GB - OK
5. tck49 - i5 12GB - OK
6. myror - unknown

OK with 16GB on 2010 iMac 27"
1. TheAnimist - i7

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Answer 11

labeck

Level 1

19 points

Sep 20, 2010 10:52 AM in response to mcsys

Same issue here. Core i7 and have had two different sets of OWC 16 gb memory and both cause random shutdowns.

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Answer 12

labeck

Level 1

19 points

Sep 20, 2010 12:18 PM in response to TheAnimist

I'm curious, the 2-8gb kits that you have that work, were they directly from Crucial? I just ordered two 8gb kits from gem and I hope it works. My two 16gb kits from owc made my machine crash, not sure if it's the imac or the ram, hoping it's the ram.

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Answer 13

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.

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Answer 14

Sep 23, 2010 7:58 AM in response to mcsys

Hi mcsys,
I have similar issues with 16 G of OWC ram. I am doing some testing now. Read my thread on this. http://discussions.apple.com/thread.jspa?messageID=12231761#12231761

peterwillem

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Answer 15

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.

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