Normally, We start our computers by the switch on the PC's form factor, but know from the previous document, there are some others ways, such as power on by keyboard , power on by mouse, Wake Up Remote, etc. these ways should be called as Soft Power. Here I will list some common ways for soft power, what conditions are required. Of course, the purpose of this chapter is to study and understand the common boot ways, if there is no need to use these soft power method, or do not use as much as possible, please do not use it. because you must keep your power supply on(Power off but not completely) while you want to use soft power. for many people, this is a waste of resources.
We can find +5VSB definition from the ATX power supply specification, but what's the function of +5VSB? We know, early AT power supply use a power button directly to turn on/off the computer. this button was usually soldered to the wires and could not be replaced easyly. but newer ATX power supply use a logic switch from the motherboard to turn on/off the power supply.