So it's all handled 'on-board' with STX, no pun intended Nice analogy, thanks So then, the solid state relay is only required when using no psu(DC step down board), or a smaller psu such as a mini that has I guess doesn't have sync capabilities on the pcie?
Does that mean, in theory, the above layout with a Mini in place of the 360 would work?
Yes. You can either:
1. Use the Add2psu. What the Add2psu does is it takes a voltage input (12 or 5v) and makes a connection (PS_on and GND). This means it is an essentially a solid state relay.
2. You can use an off the shelf 12v solid state relay. Use 12v (fan) output from motherboard, and connect the PS_on and GND to the input and output pins on the SSR.
Note, again, this is not 100% guaranteed to work. Sometimes the capacitor discharging when you turn off the pc will cause the on state to loop and never turn off.
The MINI sync output (to talk to Dynamo 360) as designed uses a signal output, instead of a power output like the Add2psu. The signal output doesn't have this problem.
It's complicated but I don't want you to think this will 100% work. I've had a couple reports of it not working when I designed the Distro 400 when using a 12v output from the motherboard.