alt Hacker News32 Gb DDR4 RAM module has a bandwidth of 25 Gb/s and costs $160. If you buy 8 of these, you get 256 Gb RAM with 200 Gb/s bandwidth at $1280. And if you buy 16 x 16 Gb modules (each at $60) then you can get 400 Gb/s of bandwidth for $960.
The only problem, you need 8 or 16 memory controllers. Memory controllers are not that expensive: Intel Core i3-14100F has 2 channel controller and costs $110, so we can estimate that 16-channel controller should cost not more than $880, and 8-channel controller should cost $440.
So isn't it better to make a cheap CPU with 16 DRAM controllers instead of this $4K gear having only 128 Gb? Or maybe 2 CPUs each having 8 RAM channels?
DDR5 costs 2 times more ($360 for 32 Gb) while not even having 2 times the bandwidth so it is not worth buying. It is more reasonable to make more RAM channels and stuff them with DDR4.
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So what I am trying to say, industry took a wrong turn. Instead of moving to over-priced DDR5, they should just make even cheapest CPUs support 8/16 DDR4 channels. Because a 32Gb DDR5-4800 module costs $360, and two 32Gb DDR4-3200 modules cost $320, so you get twice more size, more bandwidth and it costs you less. DDR5 is just a rip off.
If you want Epyc go for it. The motherboards can be quite expensive though.