Asus M3N-HD - Manual (Page 56)

2-30 Chapter 2: Hardware information
7. Chassis intrusion connector (4-1 pin CHASSIS)
This connector is for a chassis-mounted intrusion detection sensor or switch.
Connect one end of the chassis intrusion sensor or switch cable to this
connector. The chassis intrusion sensor or switch sends a high-level signal to
this connector when a chassis component is removed or replaced. The signal
is then generated as a chassis intrusion event.
By default , the pin labeled “Chassis Signal” and “Ground” are shorted with
a jumper cap. Remove the jumper caps only when you intend to use the
chassis intrusion detection feature.
M3N-HD/HDMI
®
M3N-HD/HDMI Chassis intrusion connector
GND
Chassis Signal
+5VSB_MB
CHASSIS