Asus A7N266-VM - Manual (Page 76)

60 Chapter 4: BIOS Setup
PWR Button < 4 Secs [Soft Off]
When set to [Soft off], the ATX switch can be used as a normal system power-
off button when pressed for less than 4 seconds. [Suspend] allows the button
to have a dual function where pressing less than 4 seconds will place the
system in sleep mode. Regardless of the setting, holding the ATX switch for
more than 4 seconds will power off the system. Configuration options: [Soft
off] [Suspend]