Except they are lower performance most of the time as things stand right now. In spite of the recent 3800MHz modules that TR posted about, which don't seem to be on sale yet, almost every single other SO-DIMM kit is slower than what you can get on the DIMM side for desktop/server at the top end. That's just how it is right now.
Oh and here is a 64GB module. There are a number of them on newegg alone. Some 32GB modules too. Can you fit that into a SO-DIMM? Please, show me one? https://www.newegg.com/Product/Product. ... 6ZP6HA9393
Newegg currently carries 0 32GB or 64GB SO-DIMM modules.
You talk about the prices yourself. SO-DIMMs, are on average, more expensive for their exact counterparts on the DIMM side. That's just how it is now.
I read the OP, and your suggestion that I didn't isn't appropriate. You also didn't include the part of my post where I said that if SO-DIMMs were adopted large-scale, then a lot of these issues would be mitigated. Let's not get it twisted here DPete.
Edit: here is a good example. G.Skill 3200MHz 16GB (8GBx2 kit). I think that's a pretty "mainstream" kit for a lot of PC builders these days.
SO-DIMM (only a SINGLE option from G.Skill) - 249.99
, and it has higher timings than the desktop version(s).
DIMM - 192.99
, and as stated above, it has tighter timings which help quite a bit depending on the application and CPU generation these days. I admit this is higher voltage, but 1.2V vs 1.35 isn't that huge of a deal and there is precisely zero other options for G.Skill SO-DIMM kits here. This is the most expensive G.Skill 16GB 3200MHz kit on newegg.
I don't think this comparison is a poor representation either. It's not the exception, but rather the rule of the economics of DIMM vs SO-DIMM right now. Unless there is some serious momentum happening for SO-DIMM for some reason, I just don't see them taking over.