My computer won't start unless I manually ground the green PSU wire (on the 20 pin connector that connects to the motherboard).
Once I ground the wire, the fans and lights and other accessories power up.
At this point I can press the power button on the front of the PC as per usual and the computer starts up.
If I don't ground the green PSU "on/off" control wire prior to pressing the on button, the motherboard powers up for as long as I depress the power button and shuts down immediately once I release the power button.
Is this a motherboard issue, PSU issue, or a power button issue?