Asus P4S133-VM - Manual (Page 50)

38 Chapter 2: Hardware information
P4S133-VM
®
P4S133-VM Chassis Alarm Lead
CHASSIS
+5VSB_MB Chassis Signal GND
18. Chassis Open Alarm Lead (4-1 pin CHASSIS)
This lead is intended for a chassis that supports intrusion detection.
The lead requires an external detection mechanism such as a chassis
intrusion monitor/sensor or microswitch. When any chassis component
is removed, the sensor is triggered and a high-level signal is sent to
this lead to record a chassis intrusion event. The event is then be
processed by software such as LDCM. When not using the chassis
intrusion lead, place a jumper cap over the pins to close the circuit.
Removing the jumper cap prevents the system from booting up.