TechPowerUp noticed ASUS' new P8Z77, ROG Maximus V, and Sabertooth Z77 motherboards implement UASP (USB-attached SCSI Protocol) to increase the performance of USB 3.0:
UASP changes the way the computer and connected USB devices talk to each other. It ensures more efficient utilization of bus bandwidth (5 Gb/s), resulting in higher bandwidth yield to connected devices. UASP allows connected devices to exchange multiple commands at once, reducing protocol overhead. UASP is implemented on ASUS motherboards using third-party controllers that support it.