okay, try this;
1. look for the watch size battery on your motherboard, disconnect power from the psu to the wall, remove the battery from motherboard for 5 mins , put it back in. apply power cable try to start it
2 take motherboard out from case, leave ram in it, plug psu in pc, plug monitor to the on board video output (hdmi or other) leave video card out , plug power to PSU, power button to the motherboard, does it boot when you use the power button ?