Asus PRL-DLS - Manual (Page 49)

ASUS PRL-DLS motherboard user guide 2-21
4. Chassis alarm lead (4-1 pin J3)
This lead is for a chassis designed with intrusion detection feature.
This requires an external detection mechanism such as a chassis
intrusion sensor or microswitch. When you remove any chassis
component, the sensor triggers and sends a high-level signal to this
lead to record a chassis intrusion event.
By default, the pins labeled “Chassis Signal” and “Ground” are shorted
with a jumper cap. If you wish to use the chassis intrusion detection
feature, remove the jumper cap from the pins.
PRL-DLS ®
PRL-DLS Chassis Open Alarm Lead
J3
+5V
olt
(Power Supply Stand By) Chassis Signal Ground