Asus RS720-E6/RS12 - Manual (Page 56)

4-10 Chapter 4: Motherboard information
3. 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.
2. SAS connectors
(7-pin SAS1, SAS2, SAS3, SAS4; Red)
(7-pin SAS5, SAS6, SAS7, SAS8; Blue)
This motherboard comes with eight (8) Serial Attached SCSI (SAS) connectors,
the next-generation storage technology that supports both Serial Attached
SCSI (SAS) and Serial ATA (SATA). Each connector supports one device.
These connectors function only when you install a PIKE RAID card.