Think of it as RGB lighting in DIMM format and it makes a lot more nonsense.

Nobody really buys 8gb sticks anymore, so selling 2x8gb isn't economically great. Also, there are more factors than just density in RAM pricing, but it really depends on the vendor and chip layout design.

Up to a certain point and It’s actually very dependent on the CPU.

Take Epyc processors. On certain ones, after certain RAM amount, populating all the slots causes the cpu to kick the RAM speed to a lower tier.

You’re then limited to capacities of two sticks.

Weird, but it has to do with power requirements. Abutting above the threshold had to be buffered, which increases latency.

For the same spec it's likely to be a different chip count rather than density. In theory two sticks could have higher bom... not that consumers would see such savings given the price segmentation where the appetite for higher capacities has deeper pockets.

Have recent boards/cpus fixed the instability problems people had with 4 sticks of DDR5 yet?

I was shocked when I saw folk saying you can't use 4 slots. It would mean that a one stick build would have an upgrade path but if you started with 2, you'd have to replace them.

Yes but if you want to upgrade later buying another 1x16gb is cheaper than buying 2x16gb and throwing out your 2x8gb (although it's a bit contrived since most motherboards have 4 slots).

People don't want to buy 2x8gb because there are limited slots on a motherboard and they want to upgrade when they need the extra ram.

>And shouldn't smaller capacity sticks be cheaper since they can use lower density chips?

In 2026 the bottleneck is wafer size as fabs are booked out making things for AI.