As you may or may not know, Gigabyte has a setting in the BIOS called xHCI mode. It can be set to Smart Auto, Auto, Enabled and Disabled. Disabled turns off USB 3.0 entirely and makes all the ports USB 2.0. The other three operate slightly differently, especially with regards to OS X and as you can see from my screen shots, it appears that the Auto mode is the one to pick for OS X. It's the only mode that allows the OS to see the VIA USB 3.0 hubs for example an it appears to show more information about USB 3.0 devices. I'm not sure the performance is quite there, as there's no performance benefit using either mode, but in Smart Auto the devices don't even seem to show up. Note: This only applies to the Z77, H77, B75 and Q77 boards with integrated Intel USB 3.0 ports. Also note that xHCI and EHCI Hand-off has to be enabled or the USB ports won't work at all. Edit: Also note the "HS Port Switchable" settings. On the Z77X-UD5H there are four of these and they enable you to manually set your USB 3.0 ports to USB 2.0 mode if you chose disable rather than enable. This is handy for example during installation if you don't have additinal USB 2.0 ports on your case or via a bracket.