Asus RS926-E7/RS8 - Manual (Page 64)

4-10 Chapter 4: Motherboard information
4. USB connectors (10-1 pin USB56, A-Type USB10)
These connectors are for USB 2.0 ports. Connect the USB module cable to
connector USB56, 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.
5. 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.