After using the M2 and trying to use the M4 I have finally found a power supply that works just great.
The M2 worked until I overloaded it with too many devices. The M4 was just too clever for my setup.
I have a Quanmax KEEX-2030 3.5" SBC which uses the P4-ATX connector and does not have any other ATX connector. Both the M2 and M4 needed the green wire grounded before the power supply would even start. To be fair, they are 20 or 24 pin ATX power supplies and my board is not one of those.
I asked that the DSATX be pre-programmed to ignore the PS-ON signal and the power supply that arrived works just great. It starts pefectly. It runs without problems and shuts down exactly as programmed. I recommend it highly but if you only have a P4-ATX connection then make sure your get it preprogrammed.