Hi,
I got this from FW support today (quote slightly edited by me for clarity).
“Ports 3/6 (as outlined here) are with lower power supply 0.9A@5V, which is 4.5W. All the rest ports should be good, 3A @ 5V which is 15W.”
This explains why my NVME SN850X, inside a RTL9210B USB enclosure, does not work in Slot 3/6.
For example, SN850X needs 3.3V DC and 2.8A = 9.24W (over PCIe bus), so one needs a USB port that can output more than 9.24W for it to work, so that should work in a 15W USB port, but it would not work in a 4.5W USB port.