One of the components you can save a lot of money on if you choose to do upgrades yourself on Mac Pro (2019) is – RAM. 

As I already mentioned, I bought basic Mac Pro (2019) with 32GB RAM configuration, and decided to upgrade myself. I wanted 384GB of RAM. If I wanted to buy it directly from Apple it would cost – 7.500,00€. Kit I got was 1.800,00€.

Do I have your interest now? 🙂 I think this kind of saving is definitely worth a bit of your time and effort.

So, where do we begin with this story? First, let’s establish what we want. I wanted 384GB of RAM for my Mac Pro. Also, at some point I will want to upgrade to 768GB of RAM as a max for my Mac Pro.

Apple (here in Europe) wants 7.500,00€ for the RAM kit I’m after. A lot of money, I didn’t do much researching on price, since I know that RAM is cheaper than that, I just needed to establish what RAM I need for upgrade.

Ok, lets start step by step.

CPU you have in your Mac Pro has RAM limit

There are limits for RAM configurations based on CPU you select. 8-core CPU supports 768GB of RAM in quad channel, 12-16 core support 768GB of RAM in six channel config, and only 24-28 core CPUs can support up to 1.5TB or RAM.

So have that in mind when you plan your RAM config. Maybe you will need CPU upgrade in order to get what you want in terms of RAM capacity.

What type of RAM do I need?

According to Apple, you can use DDR4 ECC R-DIMM or LR-DIMM up to 2933Mhz of speed.

You can check what RAM type you have currently installed in your Mac Pro by clicking on Apple sign in top left corner of MacOS, then select “About this Mac” and select Memory tab.

You cannot mix R-DIMM with LR-DIMM modules.

You can see that I have 384GB of RAM installed. 6 modules of 64GB RAM LR-DIMM 2666Mhz RAM.

If you need more details than this guide provides, you can find all the info here –

You need to populate minimum of 4 RAM DIMMs, so it means you will need at least 4 RAM sticks. Fewer than that is not supported. You can use only one RAM stick only for diagnostic purposes.

You can mix different sizes of the same DDR type (you can, for example, mix 8,16,32GB RAM size sticks of R-DIMM RAM type) and there are details on the Apple link I mentioned above.

If you plan to completely replace RAM in your Mac Pro, then it is up to you to select R-DIMM or LR-DIMM type, but if you want only to upgrade capacity of current RAM installed, then before ordering you need to establish which type or RAM you use – R-DIMM or LR-DIMM.

If you have lets say 4 stick of RAM operating at 2993Mhz, and you buy 4 more but at 2666Mhz – that should work – it is just that the 4 sticks that work at 2993Mhz will downgrade to 2666Mhz speed.

In general, I like to have all my RAM matching size and speed. Through years I tried everything, and many different scenarios worked, by I have peace of mind if my RAM is same size, speed…

What RAM I got?

Ok, after we learned our options and limitations, we can go further. I had initially 32GB of RAM (4 sticks of 8GB DDR4 ECC) and decided to completely pull out that RAM and replace it with 6x64GB ECC DDR4 2666Mhz LR-DIMM RAM to get 384GB of RAM I needed.

Exact model I got is Crucial CT64G4LFQ4266

Again, as with my CPU change – this is tested in production for 3 months, before I decided to write about it here. Crucial and Kington RAM generally work great for me, and I use these brands with my other machines, servers…

There is also OWC, which is specialised for Apple product upgrade, so you can check them also.

How to replace RAM in Mac Pro 2019?

Before we proceed – I’m not in any way responsible for any kind of damage you do in any way by following this guide. Make sure you know what you are doing before you proceed, you are doing this at your own risk.

Apple has pretty nice tutorial in the link I posted above in this guide, so you can check it out for reference. But lets see how I did it.

Unplug all the cables from your Mac Pro, especially power cable, and then open it.

RAM slots are on the “back” of the Mac Pro 2019

In order to get covers out, you will need to press buttons on the left to set them free.

Release them one by one. After you release one, remove RAM cover.

You don’t have to release both at the same time, each of these locks releases independent portion of RAM DIMMS.

Slide the lock to unlock

These is how your machine will look like after you remove RAM covers. You can see 4 sticks of 8GB of RAM in my machine.

Lovely thing is that inside the covers, you have illustration in which you can see how to populate RAM in slots, according to number of sticks you have.

I have six stick of RAM so I will populate according to the instructions I got in the red square below. Populate DIMMs that are coloured in white.

For more clear view, here is the picture from MacOS. I will populate DIMMs – 1,3,5,8,10,12

Now, after we know how we will populate our Mac Pro with new RAM, let’s remove old. First step 1, push ejectors out, as depicted. Opened ejectors will look like those in the circles above when opened. After you released both ejectors, pull out RAM stick as depicted with step 2. Do it gently so you don’t break something, in case you did something wrong.

Here is how released notches look like

Ok, so after you pulled out old RAM sticks, time to set new sticks in.

First, before you start – don’t force it or you can damage your motherboard or break RAM sticks. RAM stick has a notch in the middle, you have to place it correctly to match RAM slot.

In yellow square is notch on the RAM slot, in red square is notch on the RAM placed in slot. RAM stick and RAM slot are different length on both sides, make sure you align correctly shorter and longer side and the notch, and then gently press it down. Don’t force and if everything is ok, ejectors on both sides should click back in place.

Repeat the step for every RAM stick you plan to install.

Here are all my RAM sticks in place.

Double check that you used correct placement for your RAM sticks, make sure everything is placed firmly and correctly, replace RAM covers, put back housing and start your machine. If everything is ok, your machine should boot. If your machine doesn’t boot than you might done something wrong – wrong memory type, wrong placement, your sticks are not placed firmly in DIMM slots or something else…

My machine is working great from the first installation try. 🙂

If you are perhaps interested how to change CPU in your Mac Pro – here is the quide for that –

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