Asus Maximus III Extreme - Manual (Page 72)

8. Thermal sensor cable connectors (2-pin OPT_TEMP1/2/3)
These connectors are for temperature monitoring. Connect the thermal
sensor cables to these connectors and place the other ends to the devices
which you want to monitor temperature. The optional fan1/2/3 can work with
the temperature sensors for a better cooling effect.
Enable OPT FAN1/2/3 overheat protection in BIOS if you connect thermal
sensor cables to these connectors.
9. Optical drive audio connector (4-pin CD)
These connectors allow you to receive stereo audio input from sound sources
such as a CD-ROM, TV tuner, or MPEG card.
2-42 Chapter 2: Hardware information