What is the ATX Aux power connector for?

I have a Unisys branded server, with an Intel MB, and the power supply seems to be cutting out intermittently. I have ordered and recieved a replacement,(Astec SA302-3515..the exact model # on the original), but there is a 6 pin power connecter labeled P2,on the original supply, which is not on the replacement. Does anyone know what this connecter is for on the MB, and if I can safely run without it? (the specs on the MB call the connector an ATX Aux. connector)The P1 connector is the standard 20 pin ATX connector.
Thank you…
Ron