> I can just double my cheap RAM later
The thing is that this is quickly becoming impossible, even with fairly low speeds like 6000 2 DPC is not achieveable in some cases, and consumers that are buying the 4 DIMM boards aren't particularly aware of it
> Even 6000 MHz isn't necessarily "cheap low speed" RAM though, it's still a 400 MHz OC on Zen 5/14th Gen. ~$44 gets you 2x8 GB 4800 but it's ~$63 to start with 2x8 GB 6000.
I'd argue that whatever JEDEC specs intel/AMD puts up are mostly irrelevant to the reality of things, and the upgrade minded people won't be limiting speeds because of their speculative future scenario. This only leaves people who are on a very constrained budget and can't buy all the RAM at once. And they could buy a single 16GB stick and then buy another one later on when necessary. The losses from only using one channel aren't going to be as pronounced as on DDR4 either because of the 8GB's halved bangrkups and DDR5's internal channel split.
> Same for the 9900/9950X class where a lot of the users might be intentionally looking for larger amounts of slow RAM for heavier applications, not necessarily the absolute best bandwidth or latency the processor can manage.
I think DDR5 changes things up a bit here as 64GB is currently easily used and is enough for most, even heavier, workloads. Like for example for HN's audience some programming without worrying about memory being eaten up outside some more extreme cases. I agree that there's still a lot of people who'd need the ram even accounting for that, but they don't exactly need 80% of boards to have 4 slots
According to PCPartPicker, 2x48GB kits at DDR5-5200 are currently the cheapest DDR5 on a $/GB basis, so you really need to have a workload requiring more than 96GB of RAM to justify having more than two DIMM slots. That's pretty solidly into workstation territory.
Is it far off in terms of $/GB in a normal user starting with 2x24 GB 5200 at ~half the up front cost while still being able to upgrade 4 years later, if needed, when memory is even cheaper and RAM requirements are higher versus all that pro/con difference against being able to run 2 high end DIMMs at 6400 instead of 6000 or similar difference by limiting the number of slots on the board. Again, I still think this makes plenty of sense for boards focused on OC enthusiast but paying more for the 400 MHz on a tradeoff of not being able to expand just doesn't seem particularly worth it on normal boards for normal users.
Or, perhaps stated differently, other than enthusiasts purchasing the best binned low density RAM who else has what practical gains by general consumer boards having fewer slots?
People on HN can probably be assumed to want to go past JEDEC 2x48 GB RAM every time, I, again, wouldn't argue what HN should do as what the average consumer should be expected to do though. Much like I don't expect to recommend the average HN reader get the 6 core variant but it doesn't mean it's not as popular to general consumers due to price.
Same with "64 GB being easily used", true or not it's still not the capacities most are buying in new builds (32 seems to be the new common target for gamers, with 16 being the new minimum there, for example)
Even 6000 MHz isn't necessarily "cheap low speed" RAM though, it's still a 400 MHz OC on Zen 5/14th Gen. ~$44 gets you 2x8 GB 4800 but it's ~$63 to start with 2x8 GB 6000.
Simplifying it to one vendor for the sake of conversations: for boards that explicitly target 9800X OCing users it's a bit silly to see 4 slots all the time but for the majority of boards that target the whole lineup it's not nearly as silly. Same for the 9900/9950X class where a lot of the users might be intentionally looking for larger amounts of slow RAM for heavier applications, not necessarily the absolute best bandwidth or latency the processor can manage.