[nsteel]

Both the PCIe and NVLink numbers here are full-duplex bandwidth. So no, you're not missing anything, you are correct. NVLink 5.0 is far ahead (but presumably it's not actually shipping yet either). Next-gen PCIe 7.0 512GB/sec full-duplex bandwidth actually sits between NVLink 2.0 (300GB/sec) and NVLink 3.0 (600GB/sec).

NVLink 5.0's 1800GB/sec comes from 18 NVLinks, with each NVLink comprised of 2 lanes of 200Gbps (single-duplex). So in normal single-duplex numbers, each NVLink is 400Gbps, and 18 links together provide 7200Gbps. When advertised as full-duplex bandwidth that's 14400Gbps (or 1800GB/sec).

In comparison, PCIe 7.0 uses only 128Gbps lanes: 128Gbps x 16 lanes x 2 directions = 4096Gbps (or 512GB/sec).

PCIe has always been way behind cutting-edge serdes speeds. NVidia just made it more obvious to those working outside of specialist HPC and Networking. But we must cut PCIe some major slack, it has to (eventually) work on relatively cheapo hardware from hundreds of different vendors, in a restricted power and thermal environment i.e. consumer devices.

[touisteur]

Ah thanks for the detailed breakdown. You're right that PCIe has more problems to deal with.