I'm currently planning a HTPC using an Xbox One case and am planning to keep as many original features as possible, including the Xbox One power supply and front power/eject/sync assembly. I have built the touch sensitive momentary/latching circuit for the power button, but I need some advice on the startup/shutdown circuitry. The Xbox One PSU outputs 12V, so I'm connecting the motherboard using a PicoPSU and will wire the 12V directly to the graphics card. Powering on is not an issue - pressing the power button will latch together the 5V standby and Sense outputs on the PSU and switch on the 12V; I will connect the motherboard power pins either with a slight timed delay directly to the power button's momentary circuit or to the 12V source via a relay. However, I'm not sure about how to go about shutting down the system - I need to create enough of a delay between pressing the power button and the 12V cutting out for the PC to safely power down. I think maybe I could do something to affect the behaviour of the button depending on whether 12V is detected (i.e. the console is clearly in a powered on state) or not, but not sure how, maybe with a CMOS analog switch?
