Asus Maximus IV Extreme-Z - Manual (Page 65)

You can connect the front panel USB cable to the ASUS Q-Connector (USB,
blue) first, and then install the Q-Connector (USB) to the USB connector
onboard if your chassis supports front panel USB ports.
Never connect a 1394 cable to the USB connectors. Doing so will damage the
motherboard!
4. USB 2.0 connectors (10-1 pin USB12; USB34; USB56; USB78)
These connectors are for USB 2.0 ports. Connect the USB module cable
to any of these connectors, then install the module to a slot opening at the
back of the system chassis. These USB connectors comply with USB 2.0
specification that supports up to 480 Mbps connection speed.
ASUS Maximus IV Extreme-Z 2-33