Answer: The Wii

Among its modern brethren, the Playstation 3, the Xbox 360, and a simple gaming PC, the Wii is a power-consumption light weight. Under peak load the Playstation 3 consumes 200 watts of power, the Xbox 360 consumes 187, and a typical gaming PC consumes in excess of 200 watts depending on the hardware configuration.

The Wii, even when put under peak load, consumes a scant 18 watts of power–a mere 2 watts over its idle consumption of 16 watts. Although gaming enthusiasts often joke that a Wii is merely a super-charged Nintendo Gamecube, a power analysis of the two units certainly supports the joke–the Wii consumes only 2 more watts, on average, than the Gamecube. By contrast, the Playstation 3 and the Xbox 360 consume a whopping 180 and 130 watts more, respectively, than their predecessors.