How do you upgrade the RAM in the iMac Pro models? Is it even possible? What type of RAM do they use? How much RAM does each model actually support?

Please note that this Q&A explains how to upgrade the RAM in the dark gray iMac Pro (model number A1862). EveryMac.com also provides separate RAM upgrade instructions for the similar looking silver-colored "Tapered Edge" non-Pro iMac models (model numbers A1418, A1419, A2115 and A2116).

Unfortunately, unlike the 27-Inch non-Pro "Tapered Edge" iMac models -- which have a beautifully designed door that makes upgrading the RAM quick and easy -- the iMac Pro models are sealed shut and the RAM is not intended to be upgraded by an end user.

However, as is often the case with Apple hardware in recent years, there is a difference between the official company line and reality.

Photo Credit: Apple, Inc. (iMac Pro)

Identification Help (Skip)

There only is one iMac Pro line and it uses one type of RAM, so further identification practically isn't necessary.

However, further identification details may be helpful in the future. The "Late 2017" iMac Pro Model Number is A1862. Although it is common for Model Numbers to be shared by multiple models, it is likely that this one will be unique to this iMac Pro line.

For the purpose of upgrading the RAM, the original "Late 2017" iMac Pro models also can be identified by the iMacPro1,1 Model Identifier in software and externally by the 3144 EMC Number.

To locate the model identifier in software, select "About This Mac" under the Apple Menu on your computer, click the "More Info..." button, and finally click the "System Report" button.

The EMC number is inconveniently located on the bottom of the "foot" supporting the iMac Pro, but EveryMac.com nevertheless has hand documented the EMC numbers because they are a unique external identifier.

More details about specific identifiers are provided in EveryMac.com's extensive Mac Identification section.

RAM Type & Actual Maximum RAM Capacity

In marketing copy, Apple simply states that the iMac Pro is equipped by default with 32 GB of "2666 MHz DDR4 ECC memory" and it can be configured with 64 GB or 128 GB at the time of initial system purchase at additional cost.

Photo Credit: Other World Computing (Site Sponsor)

In support information, Apple originally specified a formal maximum capacity of 128 GB, but did not specify the number of slots. However, in a full teardown of the iMac Pro, site sponsor OWC discovered that it has four memory slots with the default 32 GB of memory installed as four 288-pin 8 GB modules (4 x 8 GB).

Unfortunately, OWC also determined that it was possible to install 64 GB memory modules in four slots (256 GB of RAM total), but Apple had limited the system to 128 GB in software. Thankfully, Apple removed this restriction on March 19, 2019, and formally began offering a new 256 GB RAM option, as well.

In a followup, on December 20, 2019, site sponsor OWC determined that the iMac Pro actually can support up to 512 GB of RAM.

Official RAM Upgrade Info & Cautions

Apple officially states that the iMac Pro does not have any "User-Installable Slot[s]" but it does have an "AASP-Installable Slot," which means RAM formally can be replaced by an Apple Authorized Service Provider. In reality, the iMac Pro has four memory slots, but they are inconveniently located and effectively require one to pry open the display and disassemble the computer.

If you find it perplexing that a "professional" system like the iMac Pro would be less upgradable than a "consumer" one like the 27-Inch "Tapered Edge" iMac, you're hardly alone, but this is the decision that Apple made for the iMac Pro.

RAM Upgrade Instruction Video

Although iMac Pro RAM is expensive and the upgrade process is painfully complicated, OWC has released an excellent step-by-step video for the highly-skilled:

It also is worth noting that OWC did not encounter "void" stickers applicable to memory upgrades. In theory, swapping out the memory yourself should not invalidate the warranty unless you damage an unrelated component while performing the upgrade. However, as you can see clearly from the video above, upgrading the RAM in the iMac Pro is a complicated procedure that is best left to professionals. Consequently, hiring a professional to upgrade the RAM in this Mac is strongly recommended.

EveryMac.com hopes that in the future Apple will return to iMac designs that have memory that is easy to upgrade.

iMac Pro RAM Purchase & Professional Installation Options

In the US (and many other countries), site sponsor Other World Computing sells memory compatible with the iMac Pro -- as well as all other Macs -- in addition to a turnkey professional iMac Pro RAM upgrade service by mail.

In the UK and Ireland, site sponsor Flexx sells iMac Pro compatible memory with free shipping. The company provides flat rate shipping to France, Germany, and Switzerland and inexpensive shipping for all of Europe, too.

In Germany, site sponsor CompuRAM sells quality memory for all iMac Pro models with affordable delivery country-wide and in person pick up and professional installation service available in Munich.