To be honest, I have never used it, Most of the time on a High end board, the jumper is to "force strike" the lamp. HOWEVER, I am not sure that is the purpose of JP1 on that particular power supply. Also, I have seen these power supplies become damaged beyond repair when someone was not paying attention and shorted the jumper to ground accidentally. I would strongly suggest not messing with them, especially since it is easy enough to manually strike the lamp from the menu. Joshua Wood
