TLDR: On the AC180ES-01 power supply in the SFF version of this computer (5050) does the Power Good (grey wire) adhere to the ATX specification? Meaning it supplies 5V only when Power On is shorted to ground? Or should it also be on while on standby. Thanks in advance.

The longer version is this: so I did something dumb. I used the older model SATA power connector on my SFF 5050 and shorted the 3.3V rail to the 12V rail. Why you'd change the connector spec who knows.

Now the computer works when on but when on standby the 5V and 3.3V rails are off. This makes the fan run at full speed when the computer is off (since 12V rail is present but the control is not pulled to ground by the fan controller) and kills power to USB. I'm trying to diagnose the computer to see if it's the power supply or the mobo.

The power supply seems to be fine but I have one question I can't find anywhere. On standby it supplies stable 12V on both rails and when the green wire is shorted to ground it lights up the green light and supplies 5V to the grey wire (Power OK). It also passes the self test on the BIOS. Before I spend money on a new mobo I have to verify that the 5V and 3.3V rails on the mobo don't expect to receive the Power Good signal also when on standby and that's why they don't turn on. In that case the PSU would be broken, ergo the above question.

Also if you have heard of this and know the source of the issue it'd be great. I can do an smd component swap need be.