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Comment by tommiegannert | Hacker News Reader

Thickness seems to be a major selling point here. I wonder why there aren't any board-to-board edge connectors that would allow placing RAM expansion boards next to the motherboard, instead of on top of it. Given how small laptop motherboards are nowadays, it feels like there would be some room for this.

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I think that one of the issues with edge-connectors (beyond thickness and distance as mentioned in another comment) is capacitance, which is one reason why CAMM is structured the way it is.

The issue is that the RAM needs to be close to the CPU and the edge that is the closest to the CPU is probably where designers want to put the cooling exhaust and radiator.

That's not always the case. My last three laptops have the RAM hanging off the edge of the mainboard. The SO-DIMM connectors are where the board stops, and there's "nothing" under the modules.

The CPU is actually in the middle of the MB, close to the two edges (top and bottom), but the cooling fan and heatsink are to one side, connected via some heat pipes.

SO-DIMMs are regular DDR, not LPDDR.

The biggest selling point is signal integrity and routing length. CAMM(2) is designed to be much better at that than DIMMs, which is why if this ends up being successful we will probably see it (or something similar) on desktop and eventually server too.

Whatever room there is left is used for battery/ies today and I would bet money on that if you asked customers whether they wanted RAM-sockets back or increased battery life the majority would sadly (?) pick the latter.

For something like MacBook Air it would be a problem. But MacBook Pro which has a fan and added thickness, CAMM2 would be about the same thickness.

I guess they could make a horizontal DIMM socket.

it's super flat, so maybe on the back of the board? can't make the way to the CPU shorter than that :^)

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