M2 is Memory "Gimped"

[jav6454]

On the M1 line we got the following memory configurations: 8GB, 16GB, 32GB, 64GB and 128GB. All of these are a function of doubling the density of each NAND chip, higher memory bit bus or adding more channels (dual channel). In the case of the MacBook line, it's one chip per 64-bit channel (or as one user stated x8 16-bit Memory Channels in the M1 or x16 16-bit in the M1 Pro/Max/Ultra).

In the case of the M2, we have 8GB and 16GB. But the odd one out is 24GB. 24GB can't be made by simple doubling of chip densities as that would mean the initial base storage is 12GB, which we know it's not. So, how to get 24GB? Well, there are two ways:

• Lopsided memory (1x 8GB NAND chip and 1x 16GB NAND chip) 16+8 = 24
• Binned down memory (2x 16GB NAND chip) 16+16 = 32 but with a software limiter or hardware binning to 24GB only.

Either way this looks bad as Apple intentionally gimped memory capacity on the M2 as the chip can clearly thru either configuration handle 32GB.

 

[thenewperson]

...is 2x 12GB not an option?

 

[jav6454]

...is 2x 12GB not an option?

No, NAND chips follow the rule of 2. In other words: 1GB, 2GB, 4GB, 8GB...

To make unusual configurations it's either thru triple/quad channel or lopsided configurations.

 

[DrCC]

It's probably triple channel 8GB. Anthony @ LinusTechTips thinks so. We'll see the reviews when the M2 actually ships.

 

[Stratus Fear]

On the M1 line we got the following memory configurations: 8GB, 16GB, 32GB, 64GB and 128GB. All of these are a function of doubling the density of each NAND chip, higher memory bit bus or adding more channels (dual channel). In the case of the MacBook line, it's one chip per 64-bit channel (or as one user stated x8 16-bit Memory Channels in the M1 or x16 16-bit in the M1 Pro/Max/Ultra).

In the case of the M2, we have 8GB and 16GB. But the odd one out is 24GB. 24GB can't be made by simple doubling of chip densities as that would mean the initial base storage is 12GB, which we know it's not. So, how to get 24GB? Well, there are two ways:

• Lopsided memory (1x 8GB NAND chip and 1x 16GB NAND chip) 16+8 = 24
• Binned down memory (2x 16GB NAND chip) 16+16 = 32 but with a software limiter or hardware binning to 24GB only.

Either way this looks bad as Apple intentionally gimped memory capacity on the M2 as the chip can clearly thru either configuration handle 32GB.

Non-power-of-2 densities are a thing with LPDDR, no lopsided configuration or binning required. Micron manufactures LPDDR5 in particular in 96Gb density, or 12GB per die, for example.

LPDDR5

Micron LPDDR5 DRAM handles the intensive memory needs of AI and 5G in mobile phones, with 50% faster data speeds and 20% more power efficiency than previous LPDDR generations.

www.micron.com

Also, a minor thing, but NAND is a type of flash memory; the correct term here is DRAM.

Edit: Linked the wrong page by mistake

 

[tmoerel]

It's probably triple channel 8GB. Anthony @ LinusTechTips thinks so. We'll see the reviews when the M2 actually ships.

That would make total sense. Especially with the supply chain constraints we are dealing with at the moment. It might be a lot easier to get 8Gb chips right now.....and that covers 8, 16 an 24Gb.

 

[bcortens]

No, NAND chips follow the rule of 2. In other words: 1GB, 2GB, 4GB, 8GB...

To make unusual configurations it's either thru triple/quad channel or lopsided configurations.

Actually this isn’t true anymore - DDR5 now allows non-power of 2 sizes so this isn’t necessarily lopsided…

SK Hynix to Manufacture 48 GiB and 96 GiB DDR5 Modules

www.anandtech.com

Edit: Ninjad

 

[jav6454]

Well now... that's new, apparently die sizes have changed.

 

[kvic]

• Lopsided memory (1x 8GB NAND chip and 1x 16GB NAND chip) 16+8 = 24
• Binned down memory (2x 16GB NAND chip) 16+16 = 32 but with a software limiter or hardware binning to 24GB only.

Either way this looks bad as Apple intentionally gimped memory capacity on the M2 as the chip can clearly thru either configuration handle 32GB.

Without mentioning memory controller(s), channel width, number of channels, it feels like non-sensical to talk about memory configurations.

It's probably triple channel 8GB. Anthony @ LinusTechTips thinks so. We'll see the reviews when the M2 actually ships.

If LinusTechTips had said that, they were talking non-sense.

Non-power-of-2 densities are a thing with LPDDR, no lopsided configuration or binning required. Micron manufactures LPDDR5 in particular in 96Gb density, or 12GB per die, for example.

LPDDR5

Micron LPDDR5 DRAM handles the intensive memory needs of AI and 5G in mobile phones, with 50% faster data speeds and 20% more power efficiency than previous LPDDR generations.

www.micron.com

Also, a minor thing, but NAND is a type of flash memory; the correct term here is DRAM.

Edit: Linked the wrong page by mistake

Interesting. Micron is sampling 128Gbit chips already.

So M2 Max potentially could max out at 128GB (doubling M1 Max's 64GB).

The coming SoCs for Mac Pro are supposedly 4x M2 Max. That could offer people max 512GB "unified memory". The huge-memory guys in Mac Pro user base are further cornered. I wonder if Apple will add DIMMs in the coming Mac Pro for a very tiny user group. Perhaps there is still some chance.

 

[bobmans]

No, NAND chips follow the rule of 2. In other words: 1GB, 2GB, 4GB, 8GB...

To make unusual configurations it's either thru triple/quad channel or lopsided configurations.

They're using LPDDR5 so 2x12GB is in fact possible and this is what is happening here.

 

[leman]

It's probably triple channel 8GB. Anthony @ LinusTechTips thinks so. We'll see the reviews when the M2 actually ships.

That would make total sense. Especially with the supply chain constraints we are dealing with at the moment. It might be a lot easier to get 8Gb chips right now.....and that covers 8, 16 an 24Gb.

It can't be tripple channel or the memory bandwidth would be higher for 24GB config, but they can definitely use an odd number of 8Gb modules per channel (12x8 = 96Gb per channel). I don't see anything unusual about that. I mean, Samsung sells 48Gb LPDDR5 chips.

 

[AdamNC]

Could it be set up on the 24gig SOC that 16 goes to the CPU Split between the cores equally, then 8 to the GPU? Would make some sense.

 

[quarkysg]

Could it be set up on the 24gig SOC that 16 goes to the CPU Split between the cores equally, then 8 to the GPU? Would make some sense.

Why would you want that? Both CPU and GPU can use as much memory as is available. Some use cases may need more for CPU, while others may need more for GPU. UMA makes it flexible in this respect.

 

[thunng8]

Could it be set up on the 24gig SOC that 16 goes to the CPU Split between the cores equally, then 8 to the GPU? Would make some sense.

No. Read above.

 

[MajorFubar]

I can't believe the 24GB model uses intentionally-crippled memory.
Doesn't make financial sense when the production cost has been the same to sell them in costlier 32GB Macbooks.
Worse case scenario is the 24GB uses binned chips rather than them ending up in ewaste, though as others have said, more likely some combination of 3x 8GB or 2 x 12GB
Even if they are binned chips, would it really matter? It definitely wouldn't be the first time. Exhibit A: Sinclair Spectrum 16K, and for a more recent example, 7-core GPU M1 MBA. In both instances, no one cared.

 

[Pressure]

I can't believe the 24GB model uses intentionally-crippled memory.
Doesn't make financial sense when the production cost has been the same to sell them in costlier 32GB Macbooks.
Worse case scenario is the 24GB uses binned chips rather than them ending up in ewaste, though as others have said, more likely some combination of 3x 8GB or 2 x 12GB
Even if they are binned chips, would it really matter? It definitely wouldn't be the first time. Exhibit A: Sinclair Spectrum 16K, and for a more recent example, 7-core GPU M1 MBA. In both instances, no one cared.

No, LPDDR5 offers up to 50% more RAM density so the standard 8GB becomes 12GB (96Gbit).

The M2 still uses 128-bit memory bandwidth by using two memory modules. That gives you the standard configurations using 2x4GB (8GB), 2x8GB (16GB) and 2x12GB (24GB).

 

[George Dawes]

Reminds me of my lc2 from 1992 , it has 12 megs of ram but only 10 was accessible due to cpu limitations, that was when ram cost a fortune, I think 4 megs for 400 quid ! 🤦‍♀️

 

[AdamNC]

I remember not long ago everyone freakout at the specs of the M1 only having 8 gigs and 16 gigs.... yet when it was finally in our hands we all were shocked at the performance. I think we all need to have some faith in Apple.