Skip to main content

Send us a Topic or Tip

Have a suggestion for the blog? Perhaps a topic you'd like us to write about? If so, we'd love to hear from you! Fancy yourself a writer and have a tech tip, handy computer trick, or "how to" to share? Let us know what you'd like to contribute!

Thanks for reaching out!

It’s Official: OWC’s 128GB Memory Upgrade For The 2019 iMac Retina 5K

At the completion of comprehensive compatibility testing, OWC is pleased to announce that the 2019 27-inch iMac Retina 5K is able to be user-upgraded to a mammoth 128GB of 2666 MHz DDR4 memory. The screenshot below shows a variety of utilities all showing one of the new iMacs fully loaded with RAM:

(Various macOS and third-party utilities showing a 2019 iMac loaded with 128GB of RAM)
(Various macOS and third-party utilities showing a 2019 iMac loaded with 128GB of RAM.)


Here are the prices and links for the memory upgrades now available for the 27-inch Retina 5K iMac:

64GB (2 x 32GB) – $579.99
96GB (2 x 32GB + 2 x 16GB) – $794.99
128GB (4 x 32GB) – $1099.99

Upgrades of the 27-inch iMac can be done by anyone, and require simply opening a small hatch on the back of the unplugged computer and inserting new DIMMs in the open or existing slots.

After completing the upgrade, you’ll be able to enjoy the sight of Activity Monitor showing 128 GB of physical memory and almost no memory pressure (see screenshot below). The upgrade is perfect for those who use RAM-hungry applications.

(For those who need a lot of memory, the 128GB upgrade does the trick)
(For those who need a lot of memory, the 128GB upgrade does the trick.)
Steve Sande
the authorSteve Sande
Contributing Author
Steve has been writing about Apple products since 1986, starting on a bulletin board system, creating the first of his many Apple-related websites in 1994, joining the staff of The Unofficial Apple Weblog in 2008, and founding Apple World Today in 2015. He’s semi-retired, loves to camp and take photos, and is an FAA-licensed drone pilot.
Be Sociable, Share This Post!

Leave a Reply


  • The machine comes with 4 slots

    is it better to always fill up all 4 slots?

    I’m trying to buy 2 X32GB so that I can save up and buy two more down the road, but will it be a detriment to the machine having two empty RAM.

    I’m thinking as the machine needs to operate, will expanding to 4 slots be better than pushing everything through two slots?

    I’m not sure, but I’m hoping there is an expert that can help

    • Hi Johnny! You are fine to purchase and run the 2x32GB upgrade, to leave space for later. You can even put those in alongside your Apple stock RAM for now, or run them on their own, it is fine to run empty slots in these machines!

  • If I buy a 27″ iMac 2019 – how many slots are filled in an 8Gb base build?
    thinking of adding more myself (OWC/Crucial etc)

    is it 2x4Gb or 4x2Gb?

  • I’m wondering why Apple themselves are not offering this option if it’s possible …

    • My guess is that the percent of users that need this (think, they probably want an iMac Pro or Mac Pro), is such a small percent, they do not have an incentive to increase the number of part numbers, nor buy the quantity needed to secure good supply, good price, and good quality.

      Also, Apple has a tendency to run RAM of higher spec than what is listed even on spec sheets for other PCs. That is why I always buy from a large brand name, and Mac specific RAM. Meaning, it may not have been available up to their internal specs at the time the machine was made.

      Bottom Line: Don’t buy cheap RAM (think of the cost of fried motherboard), and if you do buy 3rd party, buy good quality with a great warranty (think again, the cost of a fried motherboard).

  • Thanks for making this available so quickly. I would not consider buying the new machine without it and yours has always worked PERFECTLY in all of my Macs.