Finally found the time to test the Adapter PCBs i built to use an ATX Psu to power an Xbox.
They are plug and play to easily switch between the original psu and an atx-psu.Might be usable for casemods or laptop builds.
The adapter is built around the following basic schematic.
It properly convert the Standby voltage from 5v to 3,3v and also shifts the power_ok and power_good signals to the correct levels.
Also built a small version that can be used to build an extension cord style adapter to save some more space.
Just let me know if you have any questions about them