I need to control two computer power supplies so they turn on and off at the same time. Since the primary power supply doesn't use a standard ATX motherboard connector, I can't just splice the PS_ON lines together.
I am aware of third-party products that can do this like the add2psu - these products take 5V from a Molex or SATA power connector and use it to drive a relay to switch the PS_ON line of the secondary power supply. I'd like to DIY this, but I don't have a 5V or 12V relay handy, so I'm planning to use a MOSFET instead.
My question is - why do these products use a relay instead of a transistor? As far as I'm aware, ATX GND is tied to earth ground, so there is no need for isolation. A continuity test between the GNDs of my two PSUs confirms they are connected. Is the only reason these products use a relay is to account for the possibility of improperly grounded house wiring? If I know mine is properly grounded, it should be perfectly okay to use a FET, right?