I'm plugging into the back of my tower, so directly, should be USB 2.0, it's not blue so pretty sure not 3.0.
Ok, as a last straw you can try going through a USB 2.0 hub anyway and see what happens. What power supply are you using to power the miner? Are all the fans spinning up?
I don't have a hub lying around so I'll have to get one and try. My PSU is an ULTRA X4 750W. 12V, 56A, all fans spinning up.