Asus P5GC-MX/1333 - Manual (Page 36)

1-24 Chapter 1: Product introduction
The total current consumed must NOT exceed the power supply capability
(+5VSB) whether under normal condition or in sleep mode.
2. USB device wake-up (3-pin PS2_USBPWR)
This jumper allows you to enable or disable the keyboard wake-up feature.
Set this jumper to pins 2-3 (+5VSB) to wake up the computer when you press
a key on the keyboard (the default is the Space Bar). This feature requires an
ATX power supply that can supply at least 500 mA on the +5VSB lead, and a
corresponding setting in the BIOS.
R
P5GC-MX/1333
P5GC-MX/1333 USB Device Wake Up
3 2 2 1
PS2_USBPWR
(Default)
+5V +5VSB