Skip to main content

Fix Your Stuff

Right to Repair

Parts & Tools

Model A1419 / EMC 2806 / Late 2014 or Mid 2015. 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (ID iMac15,1); EMC 2834 late 2015 / 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (iMac17,1) All with Retina 5K displays

313 Questions View all

Buying the correct RAM Brand and Upgrading RAM in correct way


I am recently doing upgrades in my late2015 27 iMac 3,2 GHz (Skylake). Now I’ve decided to go for RAM. So by default, I’ve got 8 GB RAM(Two 4GB DDR3 1867 MHz PC3-1490 0 Unbuffered Nonparity 204-pin) placed originally as:

BANK 0/DIMM 0 4GB DDR3 1867MHz


BANK 1/DIMM0 4GB DDR3 1867 MHz


As seen above I have two empty RAM slots: I want to populate them with two 8GB RAM as to have total of 24 GB RAM. It is pretty straightforward to install RAM however:

1) Which combination of BANK’s and DIMM’s should I go for when installing RAM? There are different opinions on this, creating confusion…

2) Does having different sizes of RAM(in this case two 4GB and two 8GB) prove to be unhealthy in terms of general system performance compare to having same sizes of RAM in 4 slot (ex. four 4GB or four 8GB). Is there any issue here ?

3) There are some (not few!) negative user feedbacks about using 3rd party RAM in Late 2015 iMac; generally stating crashes after 12 to 24 months of usage. And all these crashes seem to get better after re-installing original RAM that came with iMAc. So which brand should I go for in order to avoid these setbacks as much as possible ?

Thank you in advance

Answered! View the answer I have this problem too

Is this a good question?

Score 0
Add a comment

Nintendo Switch Kits

A quick fix to get back in the game

Shop Switch Kits

Nintendo Switch Kits

A quick fix to get back in the game

Shop Switch Kits

1 Answer

Chosen Solution

The problems most people have is not using the correct RAM. Unlike a Windows system which allows you to dicker with the BIOS settings, Mac’s don’t have these tweaks available. So you really don’t want to use too high a spec’ed RAM SODIMM or of course use too slow as well.

You need 1867 MHz PC3-14900 DDR3 SDRAM SO-DIMMs (204-pin)

Buy from a name brand web site or large store like MicroCenter or BestBuy or even iFIXIT so you don’t get seconds or fake units and have a company that will support their product.

As far as which slots to use if you are just adding then just use the empty slots.

Was this answer helpful?

Score 2


So it won't make a difference if I place RAM's BANK wise or DIMM wise ? I want to go for 24 GB, my 8 GB suffices for daily stuff but when I start using Lightroom or iMovie my machine naturally slows down.. do you think 16 GB would do me good ?

The sites you mention does not have the module I want 4*2 8GB. How about this one


If you want questionable RAM then buy off of Amazon. Its best to buy directly from the company:

OWC - Memory Upgrade Kit

Here's two cheaper sets:

Crucial - 8GB DDR3L-1866 SODIMM

Kingston - KCP3L16SD8/8

And here's MicroCenter Neo Forza 8GB DDR3-1866 PC3-14900

Place your new SODIMM's in the DIMM1 slots


Thank you @danj , I appreciate it


Add a comment

Add your answer

Alican will be eternally grateful.
View Statistics:

Past 24 Hours: 1

Past 7 Days: 9

Past 30 Days: 51

All Time: 236