Why can't motherboard manufacturers just say "we only support 40mm modules on our ITX boards"?

i mean if companies want to push a standard on desktop with full atx motherboards, then i'd say, that they should certainly fit all memory sizes of that standard.

we can fit all dimm sizes we want into our current motherboards without a problem, it would be a terrible idea to have a spec setup and to have to check for height for all you buy and oh did you get the right atx motherboard for the module, that you bought? oh i guess it isn't a real standard then is it? "your memory is too tall"/"your motherboard only fits the short modules",

is the kind of stuff, that shouldn't exist in a standard and it would be a downgrade compared to full sized dimm.

I am struggling to see the advantage of camm2 on desktop compared to DIMM modules, as well

yip yip. so-dimm in comparison is at its end. that is what camm2 and lpcamm was developed for, to fix the laptop situation, where soldered memory VASTLY outperformed so-dimm, because so-dimm couldn't clock nearly as high.

About the dual channel, I thought CAMM2 was supposed to have good enough bandwidth for that not to be a concern. For example in this link you can see that DDR5 CAMM2 had a bandwidth and latency similar to dual channel DDR5-7200 C38 (keep in mind people usually go for 6000MT/s C30 kits)

a single camm2 module or socamm module or lpcamm module is "dual channel", so the equivalent of having 2 ddr5 dimm sticks in your desktop machine or 2 so-dimm sticks in your laptop.

but the issue is, that that isn't enough for apus at all, that have even half decent performance and it also wouldn't be enough for higher core count workstations for example.

so just for laptops running the future amd halo apus (if amd isn't a piece of shit and won't block modules from getting used) requires 2 camm modules.

but lpcamm is vastly worse to use due to the modules having a very awkward shape and camm2 being even worse, so that leaves you with socamm. a standard designed to be put right next to each other in servers, so it would also work great to do that for high performance apus as it keeps the traces with more than 1 modules as short as possible and also takes up the least pcb space overall then.

btw this:

(keep in mind people usually go for 6000MT/s C30 kits)

just applies to desktop cpus. that is the current am5 cpu sweetspot.

the desktop cpus we use are WAY WAY WAY less bandwidth concerned than apus.

strix halo in comparison using a 256 bit memory bus to get 256 GB/s memory bandwidth is still somewhat memory starved.

so for future higher end apus in laptops for sure you want well almost as much bandwidth as possible.

part 2:

if ddr6 doubles bandwidth compared to ddr5 (through clocks + increased per module bus width), then a halo apu could get with 2 socamm modules to at least 480 GB/s. (one lpddr5 socamm module is up to 120 GB/s shown in a presentation in a video by techtechpotato)

and with "just" 480 GB/s you are getting into somewhat reasonable range if you wanna push the gpu section of the apu really far.

for comparison the 9070 xt a very modest bandwidth modern graphics card is at 644.6 GB/s bandwidth already.

so a 480 GB/s apu would just have 75% the bandwidth of a current non high end and bandwidth efficient graphics cards.

so yeah comparing to actual graphics cards and their bandwidth requirements is what makes a ton more sense here and that basically shows you, that apus need bandwidth and are generally very starved.

Or are CAMM2 modules easier to improve on bandwidth and latency compared to DIMM modules, so that in the future it really is a better technology? Are DIMM modules reaching the end of what can be improved on?

i mean i don't know. unless we're actually at amd, intel, samsung, micron, etc... it is impossible to know i guess.

to me i'd guess, that we'll see one more generation of dimm on desktop at least (memory generation of course and not cpu generation).

but yeah i don't know, i can't know, but i'd love to know!

maybe we can get some insight with ddr6 in how far it can stretch itself bandwidth wise.

if desktop still gets full sized dimm, but laptops and mini pcs get socamm for example, then extreme overclockers could give us a decent insight into how they compare a bit more and give us some sense at least.

i'd love to see some presentation by those companies on those topics.

but one thing seems quite clear, that if we need camm modules, then socamm seems to be the best choice from all that i can see.