November 13, 2023 Tommi Kannisto HardwareTechnology

apple m3 proapplem3promemoryconfigurationtechnology

Apple M3 Pro’s Weird Memory Configuration Explained

Blog cover photo with text "What is happening with 
Apple M3 Pro's 
Memory Configuration?" and logo of M3 Pro and questionmarks.

When I first read rumors about Apple’s M3 Pro having 18GB and 36GB memory options, I thought it was an obvious error. But sure enough, the “Scary Fast” event confirmed the same amounts. M3 Pro is available instantly in the MacBook Pro 14 and 16 and certainly will be in more machines later on. How can this be?

The Logic Behind “The Usual” Memory Configuration

We have grown accustomed to the knowledge that the amount of memory (RAM) must be a power of 2, like 8GB, 16GB, 32GB, and so on. Let’s try to unravel the math for the base configuration of 18GB.

First, we need to understand why this has been true in the past.
A typical consumer processor (CPU) has 2 memory channels. In today’s PC world, it is either DDR4 or DDR5.
Both channels are 64 bits wide, making a total of 128 bits.

Each memory stick or chip size is again a size like 4GB, 8GB, 16GB, and so on.
If we have 2x16GB memory sticks in 2 channels, then we have 32GB of memory in total. This configuration looks typical, familiar, and understandable.

Breaking Down Apple M3 Pro’s Memory Configuration

Now, two new concepts have appeared to make this 18 GB memory a reality.
New memory chips have appeared with 1.5x the size – 3Gbit (2×1.5), 6Gbit (4×1.5), 12 Gbit (8×1.5), and so on. These can form memory modules of 12GB, 24GB, and so on. Modern Macs don’t have memory sticks, of course; the memory is soldered onto the same package as the CPU.

The M2 Pro had 4 memory channels, which is why it still had “normal” memory options like 16GB and 32GB. The M2 Max already had these 1.5x size memory chips installed, allowing for a maximum memory of 96GB (64 x 1.5).

Now, here’s a surprise: the M3 Pro has 3 memory channels, 25% fewer.
As we combine 3 memory channels with 1.5x size memory chips, we get 3 x 6GB = 18GB of memory.

There you go, mystery solved!

This brief explanation intentionally excludes topics like the effect of having 8GB of memory as a minimum, memory speed, and CPU core configurations. This M3 generation certainly shuffles the deck and is more controversial.

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Comments (1)

David Dzidzikashvili says:

The Apple M3 Max 3nm Chip (16 CPU cores (12 performance, four efficiency) and 40 GPU cores & 128GB) max spec – truly delivers a desktop supercomputer power & performance in a portable laptop! What an incredible performance boost and new groundbreaking features like Dynamic Caching, Mesh Shading, and Hardware-Accelerated Ray Tracing included in the GPU architecture. This is good news for the gamer community. Finally apple is closing the gap with M3 Max chip vs Windows OS based platforms with RTX 4000 series gaming graphics cards. The M2 generation had already made substantial progress in this regard, so the M3 Max 3nm chip infrastructure has again pushed the bar very high. There are other performance improvements too that the M3 offers if you are going to perform GPU-demanding tasks such as 3D graphic rendering or modelling, video and audio production. If you want to go for an insane amount of power boost then go for it M3 Max with max config & 128GB of RAM. It’s like a performance boost on steroids! But if you could wait and striving for more ( LoL why not?) then wait until the M3 Ultra comes out (x2 double the M3 Max chip = M3 ultra) in Summer 2024 with a ridiculous amounts of power and potentially up to 256GB RAM. More awesome Apple products keep coming ahead!

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