[reliabilityguy]

> So for example if you have a server with 16 DDR5 DIMMs (sticks) it equates to 1,024 GB/s of total bandwidth.

Not quite as it depends on number of channels and not on the number of DIMMs. An extreme example: put all 16 DIMMs on single channel, you will get performance of a single channel.

[metadat]

Thanks for your reply. Are you up for updating the Wikipedia page?, because as of now the canonical reference is wrong.

[angoragoats]

If you're referring to the line you quoted, then no, it's not wrong. Each DIMM is perfectly capable of 64GiB/s, just as the article says. Where it might be confusing is that this article seems to only be concerning itself with the DIMM itself and not with the memory controller on the other end. As the other reply said, the actual bandwidth available also depends on the number of memory channels provided by the CPU, where each channel provides one DIMM worth of bandwidth.

This means that in practice, consumer x86 CPUs have only 128GiB/s of DDR5 memory bandwidth available (regardless of the number of DIMM slots in the system), because the vast majority of them only offer two memory channels. Server CPUs can offer 4, 8, 12, or even more channels, but you can't just install 16 DIMMs and expect to get 1024GiB/s of bandwidth, unless you've verified that your CPU has 16 memory channels.

[metadat]

Got it, thanks for clarifying.

Happy Halloween!