"While the power is on, if I unplug the 12v cpu power from motherboard and plug back in, the pc starts normally. I tried numerous BIOS settings with no luck."
Which connectors are you unplugging? 24 pin? You do this when the mobo is powered up? Please list components with make and model.
Which connectors are you unplugging? 24 pin? You do this when the mobo is powered up? Please list components with make and model.