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Comment by nazgu1 | Hacker News Reader

In old times there were an option to upgrade ram and storage using stock parts form hardware store, but now everything is soldered.

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AFAIK now the ram gets to be way closer this way (which is why the M series gets to destroy everyone on benchmarks where it can show off that).

I think that it'd be cool to have that memory become an L4 cache and still have cheaper ram as a backing store with more capacity to fence off the CPU from the abysmal latencies that SSDs and, satan forbids, HDDs have.

Intel Lunar Lake is proving this is not necessary.

There is no technical reason that forced Apple to make the RAM soldered. They could have easily made a proprietary but replaceable socket/connector, but chose not to because of the sweet, sweet markups.

LPDDR is not allowed/available in DIMM form.

This is true but not at all relevant to anything I said, as I was not talking about DIMMs.

LPCAMM2 is available.

LPCAMM2 is also limited to 2 memory channels, so that won’t work either.

There’s a reason I said “proprietary.”

A single LPCAMM2 is a 128 bit total memory channel. The M4 uses a 128 bit memory channel.

You can have 2 LPCAMM2 slots for twice as many memory channels, like the M4 Pro.

Yes, I am aware. M4 Max would need 4 LPCAMM2 modules, and a hypothetical M4 Ultra would need 8. This sounds unrealistic (especially 4 modules in a laptop), which is why I mentioned a proprietary connector instead. There is precedence for this type of thing in the Mac Studio where the SSD NAND chips are on proprietary removable modules.

The RAM speed comes from the 512bit wide bus, not the direct connection. If motherboard makers were to support quad or octa channel interfaces, PCs would be just about as fast.

RAM throughput comes from a wide bus, but I think that nowadays memory access latency is getting pretty important to keep the CPUs working.

A CAMM2 memory based design would likely work just as well.

It is still current times in PC desktop land, and why I keep on Windows/Linux land.

There still is today; any custom built desktop can be upgraded easily. Most laptops that are more enterprise focused still have RAM and SSD slots, and replaceable batteries too.

Well you don't need to let that stop you.

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