Asus RS720-E7/RS12 - Manual (Page 61)

ASUS RS720-E7/RS12; RS720-E7/RS12-E 4-9
3. USB connectors (10-1 pin USB34, USB56; A-Type USB10)
These connectors are for USB 2.0 ports. Connect the USB module cables to
connectors USB34 and USB56, then install the modules 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.
4. Hard disk activity LED connector (4-pin HDLED1)
This LED connector is for the storage add-on card cable connected to
the SATA or SAS add-on card. The read or write activities of any device
connected to the SATA or SAS add-on card causes the front panel LED to
light up.