i'm new here and read about installing a pc in your car on an other forum and that it can be done with a normal budget. i get the main parts but the only thing i'm not wreally getting is the power supply and the shut off and boot control with the contact key....
i'm gonna use a mini itx motherboard...
its really actually easy but it depends a lot on the power supply you get.
I have an M2-ATX power supply and and it has three power inputs, Battery (12v always on), Ignition (12v , low amps), and Ground (which i connect to the frame). Ignition connects to the wire that sends a low amp 12v signal whenever your key goes in the accessory (and while the car is running) position. The power supply takes that signal and automatically turns on your car pc. There are other options as well like the PSU waiting 30s or hours depending on what you want.
All of this info is in the FAQ so you should read up