My PC motherboard is a Gigabyte Z68A-d3-b3. It is supposed to have two USB3 ports and, indeed, there are two ports on the back panel that are specifically labeled USB3 and have blue connector inserts.However, my USB3 external drive, which is plugged into one of those ports, is only connected at USB2 speed. lsusb -t output shows that Bus 3 is the USB3 hub, but lsusb -v shows that the external drive is connected to Bus 2. This makes no sense to me.lsusb -t/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M|__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M    |__ Port 1: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 480M    |__ Port 4: Dev 4, If 0, Class=Imaging, Driver=, 480M/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M|__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M|__ Port 2: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 480M/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M|__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480MFrom lsusb -v:Bus 002 Device 003: ID 0bc2:5071 Seagate RSS LLC FreeAgent GoFlex DeskDevice Descriptor:  bcdUSB               2.00Why isn't the drive on Bus 3, if that is the USB3 bus?My OS is a fully up-to-date Arch Linux 64-bit.
Confused about USB3 connection
usb;usb drive
Ok, I pulled out the cable and it is almost certainly just a USB2 cable. The inserts are white. I will have to buy a USB3 cable, and if that fixes the problem, I will mark this answer as accepted.