Comment on New Laptop Memory Is Here! LPCAMM2 Changes Everything! - iFixit Video
falkerie71@sh.itjust.works 1 month agoApple 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 be much of a concern? I’m open to corrections.
victorz@lemmy.world 1 month ago
Megatransfers? Or what does the T stand for? And how does a “transfer” (if so) translate to bytes?
bonus_crab@lemmy.world 1 month ago
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…
victorz@lemmy.world 1 month ago
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.
falkerie71@sh.itjust.works 1 month ago
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.
falkerie71@sh.itjust.works 1 month 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?
Blue_Morpho@lemmy.world 1 month ago
Wiki says M3 uses on package unified memory, so the GPU channels are also the CPU channels.