Originally Posted by kmote
All you have to do then is briefly connect the two pins of the header and the computer will start up.
I wanted to address this part of kmote's post....
1) You need to touch these two leads as he indicated by using something like a screwdriver (it works).
2) You also need to have the unit plugged in and turned on of course. It will start the computer up without a swich being pushed. All this does is bypass the switch on the case to start up your computer.
On ATX mobos (almost all the ones made in the last several years) the switch on the case sends a signal to the mobo which tells the CPU which tells the PSU to "turn me on, baby ! "
By doing the above, you are essentially bypassing that switch.