*sigh* another reason I have to get around to returning my mobo. boo-hoo.
Keep swapping parts until something works. Or take one minute to measure voltages on six wires from PSU to motherboard. Then what is actually defective could be defined. Power supply is told to power off or on by a power controller. Is that working? Those numbers posted here would say so immediately. Then you replace what is defective. Know you are not curing symptoms. And actually learn how the computer really works. That much from only one minute of labor.
The list of suspect is more than a motherboard or PSU.