27-inch mid-2010 iMac memory question

Question

Level 1

12 points

27-inch mid-2010 iMac memory question

My imac came with 8gb memory installed (4 x 2gb) and since memory is now cheap, I bought 16gb Patriot upgrade kit (2 x 8gb). I installed these into imac by removing 2 of the existing 2 gb and replacing with the 2 8gb (these were installed to lower 2 slots, lower meaning when imac was placed upside down to rest on display, these were the lower slots). The 2 new chips are the correct speed, etc. When I restart the machine, it shows only 8 gb of memory and in the system report is showing 4 x 2 gb chips. What does this mean?? I thought this should work, ie should now show 20 gb. The details from the memory page of the system report are shown below (unfortunately I didn't think to capture this data before the swap). Its as if lit thinks the old chips are still in even though they aren't; or is it somehow using only 2gb from each of the new chips? Its kind of cumbersome to take down the machine and try other combinations, but if I don't get any feedback, I'll try removing the other 2 2gb chips, leaving only the 2 new ones in. But, based on conflicting things I've seen on the internet, I'm not sure whether the new ones should be in lower or upper slots.

thanks for any feedback

Terry

memory page of system report AFTER swapping out old chips for new (its odd that they all show the same manufacturer as the old ones were original supplied by Apple, which are brand Hynix and new ones are Patriot:

Memory Slots:

ECC: Disabled

BANK 0/DIMM0:

Size: 2 GB

Type: DDR3

Speed: 1333 MHz

Status: OK

Manufacturer: 0x80AD

Part Number: 0x484D54313235533654465238432D48392020

Serial Number: 0x0882ADA4

BANK 1/DIMM0:

Size: 2 GB

Type: DDR3

Speed: 1333 MHz

Status: OK

Manufacturer: 0x80AD

Part Number: 0x484D54313235533654465238432D48392020

Serial Number: 0x0872ADA4

BANK 0/DIMM1:

Size: 2 GB

Type: DDR3

Speed: 1333 MHz

Status: OK

Manufacturer: 0x80AD

Part Number: 0x484D54333235533642465238432D48392020

Serial Number: 0x584D1CAC

BANK 1/DIMM1:

Size: 2 GB

Type: DDR3

Speed: 1333 MHz

Status: OK

Manufacturer: 0x80AD

Part Number: 0x484D54333235533642465238432D48392020

Serial Number: 0x585D1CAB

OS X Mountain Lion (10.8)

Posted on Dec 29, 2012 1:10 PM

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Answer 1

crh24

Level 3

930 points

Dec 29, 2012 1:22 PM in response to trwarren239

The maximum RAM a 2010 iMac can use is 16GB and to reach that maximum one must use 4 4GB modules. See this knowledge base article.

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Answer 2

trwarren239 Author

Level 1

12 points

Dec 29, 2012 1:27 PM in response to crh24

Thanks for the reply; yes, I have seen that article; however, there are a number of other discussions in the forum (and other places on the internet) where people have indicated that they have installed more than 16gb in this model of iMac and it works without problems. For example, see this link: https://discussions.apple.com/thread/4241780?tstart=0

so am still confused.

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Answer 3

crh24

Level 3

930 points

Dec 29, 2012 1:36 PM in response to trwarren239

trwarren239 wrote:

Thanks for the reply; yes, I have seen that article; however, there are a number of other discussions in the forum (and other places on the internet) where people have indicated that they have installed more than 16gb in this model of iMac and it works without problems. For example, see this link: https://discussions.apple.com/thread/4241780?tstart=0

so am still confused.

Certainly worth trying other combinations--especially if you use it to edit photos/video.

All of those who posted in that thread are still around and one of them may have more experience than I. I updated to 16GB when the 4's were cheap and the 8's prohibitively expensive so I never tried the 32GB combo.

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Answer 4

trwarren239 Author

Level 1

12 points

Dec 29, 2012 1:41 PM in response to crh24

thanks; I did add a reply to that thread also. Another person said they originally had 2 4gb modules and then added 2 8 gb for a total of 24, so not sure what the restrictions are.

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Answer 5

oeconom

Level 1

4 points

Feb 11, 2013 4:15 AM in response to trwarren239

Did you get it working, meanwhile?

And if so, HOW?

(I'm just planning the exact same thing)

Thx!

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Answer 6

trwarren239 Author

Level 1

12 points

Feb 11, 2013 4:36 AM in response to oeconom

no, I did not get it to work. I ended up returning those memory modules and purchased 4 4 gb Crucial modules instead - they work fine, so I now have a total of 16 gb which is probably sufficient. The cost (per gb of memory) is more but at least it works.

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Answer 7

Feb 2, 2015 7:33 PM in response to trwarren239

I know this thread hasn't been active in a really long time but, I'm thinking of upgrading my 2010 27" i5 iMac's RAM to 16GB but I'm really hesitant after reading so many threads on forums about problems with 16GB. If I order RAM, it'll be the 4x4GB from Crucial. Have you experienced problems with your iMac with 16GB since your last post? Did it run smoothly? I'm also thinking of upgrading my OS to Mavericks, does that RAM/OS combo work without problems?

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Answer 8

breid47

Level 1

8 points

Feb 4, 2015 5:15 PM in response to crh24

why not two 8GB and leave two slots open

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Answer 9

Feb 5, 2015 2:32 PM in response to breid47

Has that been tested before on the 27" i5 iMac? The Original Poster had a problem with 2x8GB and ended going the 4x4GB route, that's why I'm thinking of doing the same.

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Answer 10

rkaufmann87

Level 10

140,850 points

Feb 5, 2015 2:36 PM in response to Chief Tarun

You should be fine with Crucial RAM, use Crucial's online configurator. Another extremely trusted vendor is OWC (www.macsales.com).

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Answer 11

May 8, 2015 7:54 AM in response to Chief Tarun

i have 20gig installed on mine 2x8 and 2x2, working fine

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