5V0_MP is optional in the PICMG standard, but power cycle depends on it being present
The PICMG standard states that the use of the standby voltage is optional:
![image](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)
in this board this is used to create the P3V3_MP
![image](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)
which in turn controls the power cycle circuit
![image](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)
if P3V3 is not present, then the output value PS_ON_N is not defined.