To test power consumption today we are using a calibrated energy meter. We loaded the system with 3DMark11 and measured results at idle and load.
The system is very efficient, demanding under 40 watts when fully loaded. This load figure drops to around 30 watts when tasked with only Cinebench R11.5. The Edge HD4 consumes even less power, although the Celeron 847 performance is much weaker than the A8 4555m APU.