this post was submitted on 08 Nov 2023
246 points (92.7% liked)
Technology
60074 readers
3335 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Huge doubt here. Apple RAM is LPDDR5. That's Low Power DDR5.
Citing this site:
I'm looking at the Apple M2 Wikipedia page and it has the 800GB/s number you have, but that's gotta be something like RAM speed times number of RAM unit blocks for overall bandwidth.
Apple RAM is not magically 15 times faster than DDR5.
tl;dr
The memory bandwidth isn't magic, nor special, but generally meaningless. MT/s matter more, but Apple's non-magic is generally higher than the industry standard in compact form factors.
Long version:
How are such wrong numbers are so widely upvoted? The 6400Mbps is per pin.
Generally, DDR5 has a 64-bit data bus. The standard names also indicate the speeds per module: PC5-32000 transfers 32GB/s with 64-bits at 4000MT/s, and PC5-64000 transfers 64GB/s with 64-bits at 8000MT/s. With those speeds, it isn't hard for a DDR5 desktop or server to reach similar bandwidth.
Apple doubles the data bus from 64-bits to 128-bits (which is still nothing compared to something like an RTX 4090, with a 384-bit data bus). With that, Apple can get 102.4GB/s with just one module instead of the standard 51.2GB/s. The cited 800GB/s is with 8: most comparable hardware does not allow 8 memory modules.
Ironically, the memory bandwidth is pretty much irrelevant compared to the MT/s. To quote Dell defending their CAMM modules:
That contradiction makes it hard to balance speed, capacity, and upgradability. Even the upcoming Core Ultra 9 185H seems rated for 5600 MT/s-- after 2 years, we're almost getting PC laptops that have the memory speed of Macbooks. This wasn't Apple being magical, but just taking advantage of OEMs dropping the ball on how important memory can be to performance. The memory bandwidth is just the cherry on top.
The standard supports these speeds and faster. To be clear, these speeds and capacity don't do ANYTHING to support "8GB is analogous to..." statements. It won't take magic to beat, but the PC industry doesn't yet have much competition in the performance and form factors Apple is targeting. In the meantime, Apple is milking its customers: The M3s have the same MT/s and memory technology as two years ago. It's almost as if they looked at the next 6-12 months and went: "They still haven't caught up, so we don't need too much faster, yet-- but we can make a lot of money until while we wait."