Guys, did you know about the Etron USB 3.0 issues?
As far as I know, Z77 Extreme6 comes with 2 rear Etron EJ168A USB 3.0 ports.

Have a look at my list of links about the Etron USB 3.0 issues:
http://www.xtremesystems.org/forums/...=1#post5100398

Fortunately, the motherboard has some native Intel USB 3.0 ports which you can use in case the Etron ports fail.