this post was submitted on 08 May 2024
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[–] [email protected] 10 points 6 months ago
[–] [email protected] 5 points 6 months ago* (last edited 6 months ago)

Hopefully it can go mainstream with adoption from oems and ram kit manufacturers though I'm pretty sure it will cost a fortune for such kit that want to edges out both performance and repairability.

[–] [email protected] 4 points 6 months ago

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[–] [email protected] 1 points 6 months ago

That could be a good news of they don't skyrocket prices

[–] [email protected] 1 points 6 months ago

As a Thinkpad user since the early 2000s, I'm extremely excited to see this news after I've slowly watched all of my repair & upgrade ability be removed.

[–] [email protected] -2 points 6 months ago* (last edited 6 months ago) (5 children)

It runs at 120 GB/s...

As a Mac user that sounds pretty shit. RAM in a MacBook Pro runs at 400GB/s and that's a CPU which will be obsolete in the next few months, with a new one coming that's expected to be more like 500GB/s.

Sure, modular memory is great. But not if it comes with a performance penalty like that.

[–] [email protected] 23 points 6 months ago* (last edited 6 months ago) (1 children)

Apple M3 uses LPDDR5 and have transfer speeds of up to 6400 MT/s while LPDDR5X will have 8533 MT/s. LPCAMM2 is the connector type to replace SO-DIMM slots, it still uses LPDDR chips. According to this article, it would support speeds of up to 9600 MT/s. So unless I'm missing something, shouldn't speed not be much of a concern? I'm open to corrections.

[–] [email protected] 8 points 6 months ago (1 children)

Megatransfers? Or what does the T stand for? And how does a "transfer" (if so) translate to bytes?

[–] [email protected] 10 points 6 months ago (2 children)

Yeah mega transfers. 1 transfer is 8 bytes. the DD in DDRX is double data so it can send 2 transfers per channel per clock. CPUs pretty much always use 2 channels, so the formula is just GBps = 32 * MT/s. My PC has 6000MT/s DDR5 in a dual channel config so thatd be 192GBps.

Idk how apple is getting above 300GBps, maybe theyre counting the integrated GPU as part of the total. GPUs often have 4 or 6 or 8 channels so thatd make sense...

[–] [email protected] 5 points 6 months ago* (last edited 6 months ago) (1 children)

Thank you for going into detail.

Okay so, 1 T = 8 B. DD => 2 T/channel. And with 2 channels we get 4 T, so 4 × 8 = 32. Okay I get you. Thanks so much. 🙂

Yeah that's a crazy number with 300-500 GBps if DDR5 is doing around 200... Absolutely insane actually. But yeah, good theory about the GPU. ~~Those bastards, padding the numbers.~~

[–] [email protected] 4 points 6 months ago (1 children)

I don't think its fair to call it "padding". They're on the same die anyways and share the same memory pool through the same connections, makes sense they all have the same speed. I imagine Intel/AMD CPUs with iGPUs also share memory speeds and are both limited to how many ram channels you have configured. Apple very much could achieve that kind of speed by having more ram channels. Have the ram working in quad-channel mode, and you double the 192 GBps to 384 GBps.

[–] [email protected] 1 points 6 months ago

Good points. I retract my name-calling!

[–] [email protected] 3 points 6 months ago

Anandtech has an article about the M3 and details about it's memory speed. M3 has 100 GBps, M3 pro 150, and M3 max 400.

So theoretically there's no stopping laptop manufacturers to have multiple LPCAMM2 slots to achieve such speeds, correct?

[–] [email protected] 15 points 6 months ago

The modularity is important. You might not care about cost to replace, and affordability. Plenty of people do.

What's weirder is you compare it to a MacBook Pro with 400, when much much faster is available elsewhere. It's not an apples to apples comparison.

[–] [email protected] 5 points 6 months ago (3 children)

Why is bandwidth so important? The M2 is about half as fast as a DDR4 era x86 desktop processor with half the memory bandwidth.

[–] [email protected] 2 points 6 months ago

This memory has1/4 the bandwidth of M series Mac’s. It may be possible to match current memory with 4 chips. But that would take a lot of room. And that leaves little room for growth.

[–] [email protected] 2 points 6 months ago (1 children)

https://www.cpubenchmark.net/compare/5533vs3904vs4922/Apple-M2-Ultra-24-Core-vs-Intel-i9-11900K-vs-Apple-M2-8-Core-3500-MHz

Benchmarks are of course just benchmarks, but the single-core performance is better for the M2, and the range-topping M2 is about 2x faster than the i9.

Also, regardless of how something compares, if it is ever memory-bandwidth bound, then faster RAM should help. While most tasks may be CPU or IO bound, AFAIK there can still easily be memory bound tasks in real-world workloads.

I picked the i9-11900k for comparison since I think that was the last one to only support DDR4 (making it "DDR4 era"). Ryzen maybe faster in the DDR4 era though?

[–] [email protected] 2 points 6 months ago (1 children)

I wouldn't really trust this site. Videos that go through a lot of different benchmarks /programs and games are way better. This shows the M2 being pretty average/normal between other laptop CPUs: https://youtu.be/FWfJq0Y4Oos

And this shows M2 Ultra vs the top Intel CPU at that time: https://youtu.be/buLyy7x2dcQ

The things that's impressive about the M[x] chips are their efficiency. Apple basically lying with the performance graphs they put out is really frustrating when they have an actual amazing metric they could show: power consumption. That's what a RISC architecture is good at

[–] [email protected] 1 points 6 months ago

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[–] [email protected] 1 points 6 months ago

When the memory is shared with the GPU, bandwidth becomes much more important. A desktop will just use a dedicated GPU if it needs the performance.

[–] [email protected] 3 points 6 months ago

You're comparing apples and oranges.

The speeds you mention are defined by the memory type, not the connector.

As far as I can tell, there is no reason this connector could not, and won't be, used with more advanced memory types. Including the type in apple silicon, and beyond.