hi Kevin,
Well I bought a few 3.0 hubs today and when I use my 3.0 flash drives on these hubs, my usb 3.0 drives will run fast at 3.0 speeds protocol 3.0
so I believe the xHCI Hub is the problem not the bios or usb 3.0 xHCI controller
Maybe intel can do a driver update to fix the problem with the xHCI hub running protocol 2.1 instead of 3.0