[j-walker]

Looks like NVLink is 25GT/s while PCIe 5.0 is 32GT/s (per pair of electrical "wires").

[arnon]

On POWER9 NVLink is 300GB/s aggregated in/out.

PCIe 5.0 has a higher transfer rate, but can't aggregate links, so it's limited to 63.01 GB/s (at PCIe 5.0 x16)