Asus P4SE/U2 - Manual (Page 28)

1-18 Chapter 1: Motherboard Information
• Reset Switch (2-pin RESET)
This 2-pin connector connects to the case-mounted reset switch for rebooting
the system without turning off the power switch.
• ATX Power Switch / Soft-Off Switch Lead (2-pin PWR)
This connector connects a switch that controls the system power. Pressing
the power switch turns the system between ON and SLEEP, or ON and
SOFT OFF, depending on the BIOS or OS settings. Pressing the power
switch while in the ON mode for more than 4 seconds turns the system OFF.