Asus P4-P5N9300 - Manual (Page 36)

3-4 Chapter 3: Motherboard info
2. USB device wake-up (3-pin USBPW1-4, USBPW5-8, USBPW9-12)
Set these jumpers to +5V to wake up the computer from S1 sleep mode
(CPU stopped, DRAM refreshed, system running in low power mode) using
the connected USB devices. Set these jumpers to +5VSB to wake up from
S3 and S4 sleep modes (no power to CPU, DRAM in slow refresh, power
supply in reduced power mode).
• The USB device wake-up feature requires a power supply that can
provide 500mA on the +5VSB lead for each USB port. Otherwise,
the system would not power up.
• The total current consumed must NOT exceed the power supply
capability (+5VSB) whether under normal condition or in sleep mode.