Mastercase MC500M...It has TWO plugs from the front header which are 20-1 (19 pin) USB 3.1/3.0 Gen 1. One of them has two cables which appear to be factory connected in parallel to the plug. The other just has one cable connected to the plug. Which plug controls which of the three USB 3.0 ports on the header? My initial problem is I'm building with a ASUS Z390-E which only has ONE 20-1 (19 pin) USB 3.1/3.0 socket. I want to maximize USB port usage. BTW...Not that it may matter, but I already connected the USB 3.1 Gen 2 (type C) to the appropriate socket on the MB. Thank goodness it's a 90 degree plug. Thanks Folks
Take a look on your MB layout in the manual and you should find "U31G2_C5". It will be close to your 24 pin power connector and I think the picture you submitted shows it there. It goes in one way, cord pointing outward, fits like a glove.