Power up problem

[Geniere]

My son brought his PC over to my house as it would not power up normally. After I jumped pin 14 to ground on the MoBo power supply connector, it booted up and ran fine. When running, all power supply voltages are in spec. When off, the stand-by voltage is correct at +5vdc. The front panel on-off switch and its wires and connector are ok at less than 1ohm resistance total when switch is depressed and open when not. The on-off switch pins on the MoBo read about 1.5vdc to ground with PSU in stand-by mode. Shorting the pins does not initiate power-up. I?ve never measured the voltage on those pins before and would like to know if someone has, and what a nominal value would be. It?s a Gigabyte K7 Triton MoBo and a generic 420watt PSU.