Install and replace memory in your Mac Pro (2019)

Learn how to remove and install memory in your Mac Pro.

Mac Pro (2019) has 12 DIMM (memory) slots that support up to 1.5TB of 2933MHz memory when all 12 slots are full using DDR4 ECC DIMMs. 

8-core, 12-core, and 16-core Mac Pro models support up to 768GB of memory.

Before you begin

You can use either LR-DIMMs or R-DIMMs with your Mac Pro, but you can't mix these memory types. To check if you have R-DIMMs or LR-DIMMs installed and view your memory status, choose Apple menu  > About This Mac, then select the Memory tab.

Make sure that you use the same type of memory when installing additional DIMMs or replacing DIMMs. Learn more about Mac Pro (2019) memory specifications

Apple recommends that you use Apple-approved DIMMs. You can purchase memory upgrade kits by visiting an Apple Store or Apple Authorized Reseller. If you need to order replacement memory, contact Apple.


Check supported configurations

Mac Pro supports up to 12 DIMMs installed in configurations of 4, 6, 8, or 12 DIMMs, as shown in the images below. These images can also be found on the inside of the DIMM covers. For maximum performance, install DIMMs in a 6 or 12 DIMM configuration. If your DIMMs aren't identical in capacity, learn how to install DIMMs of mixed capacities.

DIMM configurations of 5, 7, 9, 10, and 11 DIMMs are not supported. Other configurations of 1, 2, and 3 DIMMs are for diagnostic use only.

4 DIMMs

6 DIMMs

8 DIMMs

12 DIMMs

Each number represents a DIMM slot. For each DIMM configuration, insert DIMMs only into the dark grey slots and leave the light gray slots empty.

Installing DIMMs of mixed capacities

If your DIMMs are different capacities (like four 16GB DIMMs and four 32GB DIMMs), they must be installed according to these requirements:

  • Install DIMMs in order of the channels.
  • Install DIMMs in identical pairs for each channel.
  • Install DIMMs in order of smallest to largest capacity.
  • Use only R-DIMMs or only LR-DIMMs.
  • Use a supported configuration

How to install DIMMs of mixed capacities

  1. Find out which slots to use for your DIMM configuration.
  2. Starting with the lowest capacity pair of DIMMs, install your DIMMs in identical pairs from smallest to largest capacity in order of the memory channels:
    • Channel 1: Slots 5 and 8
    • Channel 2: Slots 3 and 10
    • Channel 3: Slots 1 and 12
    • Channel 4: Slots 6 and 7
    • Channel 5: Slots 4 and 9
    • Channel 6: Slots 2 and 11

Not all memory channels are used for every DIMM configuration. For example, an 8 DIMM configuration uses channels 1, 2, 4, and 5.

DIMM Channels

The 12 DIMM slots on the right form 6 total channel pairs as shown above.


Remove or install memory

Learn how to remove the housing of your Mac Pro, remove DIMMs, and install DIMMs.

Remove the housing

  1. Shut down your Mac Pro.
  2. Wait approximately 5-10 minutes for the computer to cool down.
  3. Unplug all cables except the power cord from your computer.
  4. Touch the metal housing on the outside of the Mac Pro to discharge any static electricity, then unplug the power cord.
    Always discharge static before you touch parts or install components inside your Mac Pro. To avoid generating static, don’t move around the room until you finish installing the memory and slide the enclosure back onto the computer.
  5. Flip the top latch up, then twist left to unlock the housing.
  6. Lift the housing straight up and off of the computer. Carefully set it aside.
    Mac Pro won't turn on when its cover is removed.

Remove DIMMs

Your Mac Pro ships with DIMMs preinstalled in some or all of the DIMM slots. Before you can install memory, you might need to remove some of the DIMMs to match a supported configuration or to meet mixed capacity memory installation requirements.

  1. Slide each lock to the left to unlock and open the DIMM covers. 

  2. Remove the DIMM covers.
  3. Locate the DIMM(s) that you want to remove. Each slot is labeled with a number. Push down on the DIMM ejectors on each end of the DIMM, which slightly raises the DIMM out of the slot.
  4. Use your thumb and index finger from each hand to gently grip the DIMM at each end, then carefully remove the DIMM by pulling the DIMM straight out of the DIMM slot. Don’t twist or force the DIMM out of the socket or damage might occur. 
  5. Place the removed DIMMs into an electrostatic discharge (ESD) protective bag.

Install DIMMs

  1. Locate an empty DIMM slot.
  2. If possible, use canned air to blow dust out of the DIMM slot. Keep the can vertical.
  3. Gently hold the DIMM ends and insert it into the slot. Make sure the DIMM is aligned with the slot before applying any force to insert it. When you insert the DIMM, make sure to follow these guidelines:
    • Don’t force the DIMM. If the DIMM doesn’t insert, verify that the notch and connectors are aligned with the notch in the DIMM slot.
    • Don’t rock the DIMM into the seated position.
    • Don’t bend or twist the DIMM when you insert it.

  4. Insert the DIMM gently until the bottom edge of the DIMM is touching the gold contacts, then apply more force to fully seat the DIMM. The DIMM ejectors click into place once the DIMM is fully seated.
  5. Replace the DIMM covers. Push down on the left side of the covers until they click into place.


If you don't replace the DIMM covers, system performance may be affected.

Reinstall the housing

  1. Lower the housing over the Mac Pro.
  2. After the housing is fully seated, twist the top latch right and flip it down to lock it.


    Top: Locked position (dots match)
    Bottom: Unlocked position (dots do not match)
  3. Connect the power cord, display, and any other peripherals. 


Verify your memory

To check the status of your memory, choose Apple menu  > About This Mac, then select the Memory tab.

If your DIMMs should be configured in different slots to maximize performance, macOS notifies you with recommendations for which slots to use for your currently installed DIMMs.


Other configurations

These DIMM configurations should be used only for troubleshooting issues with your memory:

3 DIMMs

2 DIMMs

1 DIMM


Learn more

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