Why the MacBook Pro 16" with M3 Max 14-core CPU and 30-core GPU model only have 36GB or 96GB options?

[hajime]

Hi, given that it can be configured from 36GB to 96GB unified memory, why the options for 48GB and 64GB are unavailable unless we choose 16-core CPU and 40-core GPU configurations?

Another strange things is why the 16-core CPU and 40-core GPU model doesn't allow 96GB unified memory but 48GB, 64GB or 128GB?

 

[Bigwaff]

Why you think memory needs to be only in options based on powers of 2 ?

 

[crazy dave]

The cut down M3 Max has 6 memory "slots" while the full version has 8. The RAM modules come in sizes of 6, 8, 12, and 16 GB. Thus for the cut down Max you could theoretically have 36, 48, 72, and 96GB. The full version could in theory come in sizes of 48, 64, 96, and 128GB. The reason they don't come in some of the middle specs has to do with product differentiation and, even more importantly, logistics. The soldered memory (and soldered storage) means Apple has to pre-bake the RAM amounts (and all the combinations with storage) from the factory line. To simplify their logistics and differentiate the lower tier and upper tier products, especially for the relatively low volume Max, Apple doesn't offer every possible combination.

 

[alfogator]

Hi, given that it can be configured from 36GB to 96GB unified memory, why the options for 48GB and 64GB are unavailable unless we choose 16-core CPU and 40-core GPU configurations?

Another strange things is why the 16-core CPU and 40-core GPU model doesn't allow 96GB unified memory but 48GB, 64GB or 128GB?

The lower core count parts have a 300 GB/s max memory bandwidth while the 16 core parts have 400 GB/s. You get these values by connecting several memory units in parallel, so in the first case you have 3 channels at 100GB/s each and 4 channels for the 16. Each memory unit is of some given sizes, so the memory configurations you can get are always multiple of 3 or 4.
The cheaper config gives you less memory for each tier and also lower max memory speeds. These speeds are only relevant for some GPU tasks anyway, the CPU alone is not able to use the full available memory bandwidth so unless you're doing workflows like LLM inference where you're limited by memory throughput you won't see much (or any) performance penalty.

 

[Fomalhaut]

Do we expect the future M4 Max to follow the same RAM layout and options for the binned SoC?

I find the M3 Max options to be frustrating. I’m sure many people would be happy with the lower GPU core count, even grudgingly having to accept reduced CPU cores (as per the M3 Max), and would be OK paying $200 to upgrade to 48GB RAM, or $400 to get 64GB, but don’t want to pay $800 to get an unnecessarily large 96GB. Instead you have to pay $500 or $700 to get your RAM upgrades because you have to choose the non-binned CPU/GPU options as well.

Apple could offer 48GB in the binned SoC (6 * 8GB) or 72GB (6 * 12GB) but choose not to, so that buyers are forced to upgrade to the full Max SoC for at least an extra $500.

I hope they change this for the M4 Max!

 

[alfogator]

Do we expect the future M4 Max to follow the same RAM layout and options for the binned SoC?

I find the M3 Max options to be frustrating. I’m sure many people would be happy with the lower GPU core count, even grudgingly having to accept reduced CPU cores (as per the M3 Max), and would be OK paying $200 to upgrade to 48GB RAM, or $400 to get 64GB, but don’t want to pay $800 to get an unnecessarily large 96GB. Instead you have to pay $500 or $700 to get your RAM upgrades because you have to choose the non-binned CPU/GPU options as well.

Apple could offer 48GB in the binned SoC (6 * 8GB) or 72GB (6 * 12GB) but choose not to, so that buyers are forced to upgrade to the full Max SoC for at least an extra $500.

I hope they change this for the M4 Max!

Given what they did with the iPad Pro, tying memory and storage, I wouldn't bet on it.