Aaeon SBC-775 Quick Installation Manual page 7

The SBC-775 can support an advanced soft power switch function
if an ATX power supply is used. To enable the soft power switch
function:
1. Take the specially designed ATX-to-PS/2 power cable out of
the SBC-775's accessory bag.
2. Connect the 3-pin plug of the cable to J7 (ATX feature
connector).
3. Connect the power on/off button to J1. (A momentary type of
button should be used.)
SBC-775 Installation Guide 7