Interesting... My Motherboard says it has a USB Type C port on the back. Haven't tried that. I've been using the USB3.1. Also, when I used the USB 3.0 via my Inatek PCIe card, my PC would not shutdown. I would attempt to shut it down, and then the system would just boot backup. So then I plugged the Rift S back into the USB3.1, all was normal.
I'm going to look at that USB C thingy...
probably can't, because I use the GTX1080, and maybe the Type C is associated with the onboard graphics of the MB?