Hector Martin

But I do remember a detail that eliminated my confusion - it was an NVMe adapter which used a proprietary cable to connect to the card slot - Thunderbolt was the _other_ option on the platform for eGPU. I went what I thought was the harder road.

Yeah it's a hacky piece of shit. Thunderbolt doesn't run over normal USB 3 A/B connections at all. Neither does PCIe; they abuse the GND and VCC pins for sideband signals, and use cable shield for ground.

But this all works well for you because PCIe is actually brilliant on every level. You could probably run it over barbed wire. The same cannot be said about Thunderbolt in the slightest.

To paraphrase @marcan42, iirc: "you could run pcie over different lengths of wet string"

I don't think I went as far as *different* lengths of wet string... but yeah :-)

Conductivity aside, that would create Hopper-like delays in the signal lines, yes?

Pcie spec involves relatively robust link training so that it's safely independent of the physical medium. As a result, it's capable of running over just about anything that's conductive.