... of the power test suite.b. Power on the supply of power, will hear "DuDu" ring, if no flicker then the power supply output voltage is ... too, then the power is failed.SpecificationVoltage source : 20/24pin (ATX-connector)Voltage test : +12V,-12V,+5V,-5V,+3.3V,5V Stand by ( ... SB) 12V power Good (PG)Connectors : Floppy, HDD, CDROM, ...