I used to have the same problem but now my hackintosh can see usb 2.0 devices in the 3.0 slot. I installed the macbookpro 10,1 update that came out recently and it started working after that.
i have a gigabyte Z77-DS3H rev 1.1 f9 with an intel 3570k i5
Most USB 2.0 devices don't work in USB 3.0 ports.
Things that don't work are mass storage devices i.e.: my ext HDs and flash drives and my Apple Wired Keyboard.
Things that do work are my DBT-120 USB Bluetooth and Razer Diamondback mouse.
I have both EHCI and XHCI handoff enabled in BIOS. I've tried all combos of this but nothing works.
Any ideas?
I can have USB 3.0 on my GIGABYTE X58A-UD3R FB??
I have USB 3 working on my Asus Sabertooth x79. Make sure to select USB 3.0 - 3rd Party = CalDigit using Multibeast 5.1.3. Am getting steady 84mb speeds. Using ML 10.8.2. Bios 2002