Well, the G4 Cube has its own custom external power supply. The power supply (on the left in this picture: http://victor.orly.com/mdx-cube/Cube-PS.jpg ) supplies the Cube itself with 28 vdc. Why 28v? Because the Cube has the proprietary video card connector, ADC (Apple Display Connector) for plugging in the now discontinued older Apple flat screen displays and supplying power, video signal and USB over the same cable. The video cards don't have to use that, they also have a VGA connector (some other cards have ADC and DVI). Internally, other components are 12, 5 and 3.3 volts, stepped down by the internal DC-DC Board (voltage regulator module, http://victor.orly.com/mdx-cube/Cube-DC-DC-Board.jpg )

Personally I don't need the 28 vdc since I'll likely use the VGA output. I may rig up a way to supply just 12 volts to the computer, if the DC-DC module allows that. Otherwise I'll have to use the inverter.

Victor