Comment by klempner
9 hours ago
> Not USB-C complexity
3.2 Gen 2x2 (and the occasionally relevant 1x2 if you have a weak cable) are USB C only.
USB C ports and cables have 4 USB 3 "superspeed" lanes rather than two. When you use an A to C cable only one pair of those connects. The point of the "x2" modes is that they use the second pair of lanes that would otherwise go unused.
Except of course they don't always go unused. DisplayPort Alternate Mode sends DisplayPort over those two "unused" lanes getting you USB 3 data alongside a half speed DisplayPort connection. (or alternatively full speed DisplayPort on all four and only USB 2), and then of course Thunderbolt 3 and modern USB4/TBT4 use all four lanes and tunnel everything.
> The point of the "x2" modes is that they use the second pair of lanes that would otherwise go unused.
Thank you for answering a question I didn't know I had