I've got a WD Passport hard disk with "superspeed" USB 3.0 support. When I use my USB 3.0 flash drive (this is a Lenovo X220 laptop), USB 3.0 consistently works. But when I use the passport drive, almost without fail the connection drops to USB 2.0. Touching the cable seems to immediately trigger the problem, but it seems to happen on its own though.
I've got another cable on order right now... but is it likely the cable's the issue here? Is there anything else I can check?