DDR5 is currently more expensive than DDR4 because it is new and volume is still ramping. What SemiAccurate wants to know is what will it look like in the server space.
For the past few weeks SemiAccurate has been looking in to the next gen/2022 server space and found some interesting details. Both Intel’s Sapphire Rapids and AMD’s Genoa use DDR5 memory and some have HBM as an option. DDR5 is significantly faster than DDR4, we told you about the speeds Sapphire Rapids, Emerald Rapids, and Genoa would support here.
So speed and performance isn’t an issue, what about cost? This is where things get tricky because initial production is always limited, prices high, and selection is sub-optimal. The DDR5 itself will likely follow the normal pricing curves, there is nothing we can see that indicates it will be different this time, but what about the boards?
This is where things get interesting because the speeds of DDR5 require a whole new level of engineering for signal integrity. Sure JEDEC did a great job keeping pin counts down which has a direct bearing on costs, but the speeds move it in the other direction. You need higher quality materials, better isolation, and much more. Luckily for everyone the initial fears of 1 DIMM per channel (1DPC) for DDR5 turned out not to be the case, both Sapphire and Genoa support 2DPC out of the box.
How did they do it? Layers and more layers. The reference design boards for Sapphire Rapids servers have 16 layers, 1/3 or so more than DDR4 boards of similar capability. Yes you get more for your money but those extra layers are obviously going to cost a lot more for the added materials, better materials, and lower yields. 1DPC boards will be out there as well and should be significantly cheaper but if you need capacity, and most servers with the core counts of SPR and Genoa do, you are kind of stuck with the 2DPC boards. That said they work and will be fast.S|A