I needed to put a Mac Mini in someone’s house.

But it had to run Windows XP.

Headless.

And restart automatically after losing power.

The headless part was handled by our master solderer, following the instructions from the nice folks at Mythic Beasts. They also explain the power-on problem, but don’t provide a direct Windows solution.

To make a long google short, download WPCRS120.EXE from Japan, run it, run the included installer, reboot, run wpcrset.exe, set {Bus 0, Device 31, Function 0, Register A4} to 0, and reboot again.

Before each of the required reboots, you’ll see this: