Original Power Supply
The original Xbox 360, introduced in 2005, came with a 203-watt power supply. This unit is noted for the six-opening end that is inserted into the console. These six square-shaped openings are separated horizontally by a thin rectangular gap. Like all 360 power supply connections prior to the introduction of the "slim" model, the connector is keyed on one side to assist in proper insertion.
Second Iteration
The second version of the Xbox 360 power supply corresponds with the introduction of a more efficient console. This power supply, although compatible with the older version, only consumes 175 watts max. The connector end of the console is identical to the older, with the exception of the thin horizontal section in the middle bisected by a small plastic divider.
Version Three
The third version of the 360's power supply further reduces power consumption, down to 150 watts. The connector is identified by a second thin piece of plastic that divides the thin gap present above the six square openings, present in all power supply connectors.
Xbox 360 "Slim"
The first major change in 360 power supplies, the "Slim" uses a more conventional connector at the console side. The connector eschews the large, keyed square synonymous with the traditional appearance of the power supply. This makes this power supply the first that cannot be used with any other Xbox 360 console other than the S. This power supply, while remaining large and external, consumes a relatively low 135 watts.