Asus TS100-E8-PI4 - Manual (Page 48)

Chapter 3: Motherboard information 3-8
2. 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.
3. USB 2.0 connector (10-1 pin USB78, 10-1 pin USB1011; A-Type USB9)
These connectors are for USB 2.0 ports. Connect the USB module cables to
connectors USB78. These USB connectors comply with USB 2.0 specification that
supports up to 480 Mbps connection speed.