Right from Gigabyte's website.
Up to 12 USB 2.0/1.1 ports (6 on the back panel, including 2 eSATA/USB Combo, 6 via the USB brackets connected to the internal USB headers)
1 x Renesas D720200 chip and 2 x VLI VL810 hubs:
Up to 4 USB 3.0/2.0 ports (2 on the back panel, 2 via the USB bracket connected to the internal USB header)
* The USB 2.0 signals of the USB 3.0/2.0 ports on the back panel are from the South Bridge.