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Comment by jcalvinowens | Hacker News Reader

I've asked in the past, and been told that a even a 2x-3x difference in the amount of RAM made such a negligible difference in cost it was decided to go with the larger amount. I frankly have a hard time understanding how that can be true... but I can't really imagine why they wouldn't be honest with me about it.

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> I've asked in the past, and been told that a even a 2x-3x difference in the amount of RAM made such a negligible difference in cost it was decided to go with the larger amount

That doesn't pass the sniff test. Look at retail RAM prices. Certainly the magnitude of the price is quite different than buying individual RAM chips at quantity, but the costs do scale up as RAM size goes up. Hell, look at RAM chip prices: you are definitely going to increase the price by more than a negligible amount if you 2x or 3x the amount of RAM in your design.

Also consider the Raspberry Pi, since the article mentions it quite a bit: RAM size on the Pi is the sole driver of the different price points for each Pi generation.

The retail price of a finished product has very little to do with the cost of individual components and more with profit margins or customer segmentation.

At quantities of 100, 512Mbit of RAM is $1.01 [0]. 1Gbit of RAM is $1.10 [1]. 2Gbit is $1.05 [2]. 4Gbit is $1.16 [3]. It is only at 8Gbit that prices substantially increase to $2.30 [4].

So no, at those sizes price really does not change all that much, and installing 512MB of RAM instead of 64MB only increases the product's cost by $0.15. It's a commodity made on legacy processes, things like packaging, testing, and handling far outweigh the cost of the actual transistors inside the chip.

[0]: https://www.lcsc.com/product-detail/DDR-SDRAM_Winbond-Elec-W...

[1]: https://www.lcsc.com/product-detail/DDR-SDRAM_Winbond-Elec-W...

[2]: https://www.lcsc.com/product-detail/DDR-SDRAM_Samsung-K4B2G1...

[3]: https://www.lcsc.com/product-detail/DDR-SDRAM_Samsung-K4B4G1...

[4]: https://www.lcsc.com/product-detail/DDR-SDRAM_Samsung-K4A8G1...

At a company I worked at they explicitly told us they will do anything to avoid upgrading the hardware from 1GB to 4GB because it increases costs. They would rather we optimize the software to use less RAM than upgrade the hardware.

I remember arguing as well with people about 0.10$ components. They told me it was a no go, not even a point of bringing it up. Sometimes even a 0.01$ is a big deal.

Yeah, prices do indeed go up beyond 1GB - but we're talking about systemd needing 8MB of RAM. With small RAM chips there is more variation between parts than there is between sizes - hence the linked 2Gbit chip being cheaper than the 1Gbit one despite both of them being the cheapest option at LCSC. Those 8MBytes of systemd might push you from needing 1Gbit of RAM to 2Gbit, but it isn't going to push you from 8Gbit to 64Gbit - and as shown 1Gbit and 2Gbit don't meaningfully differ in price.

There are a lot of other factors involved with respinning hardware which make an upgrade a lot more expensive than simply a BOM increase. I can definitely understand why an existing product wouldn't be upgraded, but for a new product going to a bigger memory chip is a far smaller hurdle. The added software engineering time for working around RAM limitations can easily outweigh any money saved on the BOM, with choosing a smaller chip ending up being penny-wise pound-foolish.

And indeed, an extra $0.10 or even $0.01 can be a big deal. But those cheap systems usually aren't powerful enough to meaningfully run Linux in the first place: just because you can technically hack a $1.00 RP2040 or ESP32 into running Linux doesn't mean it is a good idea to actually do so. If your product is both cheap enough that it represents a significant fraction of your BOM and high-volume enough that you can afford the engineering time in the first place, why not use a purpose-built embedded OS like Zephyr?

Even Apple produced laptops with 8 GB RAM just recently, which they sold for hundreds of dollars with huge margins (AFAIK). If you're going to produce something with $50 cost, 1GB RAM cost will be meaningful.

In my experience production people will eat your soul for a single resistor if they can cut costs on it.

That RAM is unified though, not a good comparison.

Also, just because something holds true at large numbers doesn't mean it scales all the way down. Either due to economies of scale, or the negligibly different architecture/components at that size.

The RAM is ordinary LPDDR5 organized into what is de facto just a large number of memory channels. It's not HBM or anything exotic, the cost of the RAM chips themselves are the same cost they are anywhere else.

That is the Apple tax on everything the fruit company sells, they always push the margins as far as fans are willing to pay for.

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