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Just to put some numbers on it.

DDR5 Latency = 16.67ns

DDR5 Bandwidth = 64GB/s

Now, keep in mind, this doesn't account for things like dual or quad channel which bumps up the bandwidth even further though doesn't really affect latency.

The fastest and most reasonably priced consumer NVMe I could find:

NVMe Latency = 200000ns

NVMe Bandwidth = ~3GB/s

The fastest consumer (or low enterprise) grade persistent storage is terribly slower and takes longer to respond than the cheapest DDR5 ram.



isn't optane latency more like 8 µs or 8000ns[1]?

Still waaaaaaaaaaaay slower than ram, but getting closer. Before giving up on optane, intel used to make memory modules with optane on them (as a form of backup I think)

[1]: https://www.intel.com/content/www/us/en/products/docs/memory...


I didn’t know about those Optane SSDs they are very interesting and I will look into acquiring one if they are available for consumer hardware.

From the mentioned article:

“Bandwidth problems can be cured with money. Latency problems are harder because the speed of light is fixed; you can’t bribe God". David Clark




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