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RobotToaster

I don't get it.

Isn't 2x8gb faster than 1x16gb since it will run in dual channel?

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

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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.

It's the signal integrity and applies to desktop class boards, as well. A fully populated four DIMM Intel or AMD board will need to run at a slower mega transfer rate than a two DIMM board (or a four DIMM board with only two DIMMs populated)

I have a fully populated server with 2x7K62 and 16x64GB (3200 mhz) for my home lab. Do you know how to check if I am affected by this?

Easiest way would be to put two dimms in one channel, check your mem spped, put 1 dimm in 2 channels, check mem speed, then repopulate as you had, check mem speed.

Sometimes having more, but slower ram, is still better than having less, but faster ram.

As always, measuring your real world use cases is the ultimate test.

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.

Lower density chips are cheaper, because they can be made in previous generation fabs churning out previous generation wafers with previous generation equipment. So there isn't a choice between making a high or low density wafer from the same fab line.

Is there all that much using larger node sizes for new RAM?

Or is it just binning by defects, the lower sized parts are just the full size but with defects disabling large chunks of the silicon as I would expect?

Are there any older generation fabs making DDR5-6400 like the article discusses? As far as I know those ones were mostly upgraded to newer processes and the long lifecycle fabs have targeted slower speeds.

It wouldn't make sense to throw the previous gen machinery to the trash if it can keep making profitable memory. Esp as smaller module capacities become more common now with the price increases. You need to update the chip design for DDR4 -> DDR5 but there's no magic flashy business in DDR5 meaning it could only be implemented in the latest process node.

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