M2 max and default RAM speculation

[senttoschool]

The current Intel Mac Pro supports up to 1.5TB of RAM. If Apple made a Mac Pro with 2x M1 Ultra glued together, it would theoretically support a max of 256GB of unified RAM. Not bad. But still too far behind the 1.5TB total of what an Intel Mac Pro can support.

So the M2 must raise its max RAM support, right?

• M2 --> 32GB max
• M2 Pro/Max --> 128GB max
• M2 Ultra --> 256GB max
• 2x M2 Ultra glued --> 512GB max

This gets us closer. Apple will have to ignore any customers who need more than 512GB until they get to M3 or M4. Or perhaps they'll support 512GB of unified memory and then support additional non-unified RAM expansion slots for the Mac Pro. For example, Intel's upcoming Sapphire Rapids supports 64GB of integrated HBM2 memory and DDR5 expansion slots, giving it 5 tiers of cache (L1, L2, L3, HBM2, DDR5).

If Apple raises the max RAM capabilities with the M2, I wonder if they'll also raise the default RAM that comes in base configurations. For example, new M2 Air will get 16GB of RAM by default. M2 Pro/Max will get 24GB. The last time the Macbook Pro increased its base RAM configuration was in 2014, which would be 9 years in 2023.

 

[T'hain Esh Kelch]

I think the workstation chips will be separate from the M line, where RAM is not connected directly to the chip. They will be slower, but RAM scaleability will be better, and one could assume Apple will then throw more cores/chips at it, or increase voltage/whatever to make them even more powerfull.

Or they will create some monster where you can add dual M1 Ultra chips on PCIe cards or something, and thus have the option for up to four double M1 Ultra with 2x128 Gb RAM. No idea if that is even possible or it would making cooling impossible.

One last possibility is that the market for professionals that rely on 500+ Gb RAM is so small, that Apple will let them go.

 

[senttoschool]

One reason why Apple might go with the RAM expansion slot route is that both AMD and Intel's latest server chips already support 4TB of max RAM. While I don't think Apple wants to compete with server chips, Apple needs a long-term scalable way of expanding RAM.

So I could see M2 both doubling max unified RAM and giving Mac Pros DDR5 expansion slots.

 

[leman]

Well, my “solution” to this is a NUMA architecture with multiple compute boards (each with a SoC and integrated fast RAM) connected to a pool of shared slotted RAM. But there are also obvious drawbacks to such an architecture (cost , complexity, software support) which might make it less feasible for a nicht product like the MP.

If Apple instead goes with a more conservative uni-SoC approach, I don’t see any perspectives for expandable RAM in the MP. High bandwidth unified RAM is one of the main selling points of the architecture, and they are not going to cripple it by downgrading the RAM specs. In that case we will probably see 512GB/1TB RAM tops (at a truly scary price levels).

 

[senttoschool]

Well, my “solution” to this is a NUMA architecture with multiple compute boards (each with a SoC and integrated fast RAM) connected to a pool of shared slotted RAM. But there are also obvious drawbacks to such an architecture (cost , complexity, software support) which might make it less feasible for a nicht product like the MP.

If Apple instead goes with a more conservative uni-SoC approach, I don’t see any perspectives for expandable RAM in the MP. High bandwidth unified RAM is one of the main selling points of the architecture, and they are not going to cripple it by downgrading the RAM specs. In that case we will probably see 512GB/1TB RAM tops (at a truly scary price levels).

Why not just update macOS to take advantage of another tier of RAM? Doing the multiple compute boards approach seems way too complicated for a niche market. The smaller unified RAM would still be of huge benefit to applications that don't exceed it.

I think 1TB of unified RAM is out of the question for M2, and even 512GB is just speculation at this point. If the M2 can only do 256GB of max unified memory like 2x M1 Ultra, then I don't see how Apple could replace the Intel Mac Pro in 2022/2023.

 

[leman]

Why not just update macOS to take advantage of another tier of RAM? Doing the multiple compute boards approach seems way too complicated for a niche market. The smaller unified RAM would still be of huge benefit to applications that don't exceed it.

Multi-tiered RAM can probably be done transparently to software (the SOC RAM will essentially work as L4). Compute board approach would require dedicated software support.

I think 1TB of unified RAM is out of the question for M2, and even 512GB is just speculation at this point. If the M2 can only do 256GB of max unified memory like 2x M1 Ultra, then I don't see how Apple could replace the Intel Mac Pro in 2022/2023.

Different use cases. If Apple is targeting the rendering/software dev/ML markets, having faster RAM and more GPU RAM can be more valuable than just having more system RAM.

It’s not like cutting edge datacenter systems (e.g. Grace/Hopper) offer more RAM per processing capacity.

 

[satcomer]

I'm thinking Apple is going to do multiple chips in new Pro like in past!

 

[ian87w]

I really really hope that 16GB will be the base for M2. Apple only sells pre-configured base models in my country, so currently we can only buy M1 Macs with 8GB of RAM. If one wants 16GB of RAM, one has to buy the 14/16" Macbook Pro. Hopefully M2 will change that.

 

[darngooddesign]

So the M2 must raise its max RAM support, right?

RAM is one of the distinguishing factors between the M1 and M1-Pro so I doubt it. The M2 series will be faster versions of the M1 series with the same RAM limits and number of core types. The M3 or M4 might give the low end computers more than 16GB of RAM, and knowing apple the base wills till have 8GB, but not before then. The MacPro, whether it has an M1 or M2, will have a seriously high RAM limit, but that's no indication on what the entry level computer will get.