The total RAM of an iMAC 5k goes low after installing a new memory chip

Question

The total RAM of an iMAC 5k goes low after installing a new memory chip

Hello People,

I have an iMAC 5k retina with 16Gb of memory (installed as 2x8Gb chips). When I followed the instructions and added 2x2Gb DIMM's to the memory compartment, then the iMAC started showing up the total memory as 10Gb.

After removing the newly added memory DIMM's, the iMAC again showed the total memory as 16Gb.

Looks like one of the 8Gb DIMM's get deactivated and only one of the 2Gb DIMM's gets activated when all four DIMM's are inserted (which brings the total memory to 10Gb).

Please let me know if anyone else has seen this behavior too, and any potential solutions to make all four DIMM's work at the same time.

I appreciate your time on this.

Cheers,

A

iMac with Retina 5K display, OS X Yosemite (10.10.2)

Posted on May 4, 2015 12:16 PM

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Answer 1

Best reply

iCare

Level 4

2,490 points

May 5, 2015 5:09 PM in response to ankitchadha29

Where did you get the new 2X2 GB SO-DIMM's? Are you sure that they meet the specifications required by your iMac? What does the label on the DIMM's say? According to the Apple article highlighted below the SO-DIMM's need to meet the following requirements.

iMac: How to remove or install memory - Apple Support

PC3-12800
Unbuffered
Nonparity
204-pin
1600MHz DDR3 SDRAM

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Answer 2

SeaPapp

Level 7

26,486 points

May 5, 2015 5:08 PM in response to ankitchadha29

Neither Crucial nor OWC, the only two places you should buy Mac memory from, sell 2gb modules that meet spec for the retina iMac. I believe that you have incompatible memory.

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Answer 3

May 5, 2015 5:12 PM in response to SeaPapp

So these ones are from an old MAC-mini.

As of now, the system seems to be chugging along at the expected memory (20Gb). However, I've noticed some oddities: MS-Word pops up whenever I try to shut down the system and nothing happens unless I manually kill the MS-Word process.

Guess I'll need to buy new and Crucial/OWC RAM to help me get the desired performance.

Thanks to all who replied!

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