The following is a guide that will help you determine the differences between Xbox 360 power supplies.

Since the release of the Xbox 360 there have been several major (and many minor) motherboard revisions. All are introduced in an attempt to build systems cheaper and to allow them to run cooler and on less power. Note that there is no clear divide between the appearance of motherboard revisions in their retail packaging.

The initial motherboard version was known as "Xenon" and used a 203W power supply. The "Zephyr" revision was largely the same aside from the addition of an HDMI port. "Falcon" incorporated a 65nm CPU, but still used a 90nm GPU, and came packaged with a 175W power supply. "Jasper" (released late August or early September 2008) used both a 65nm CPU and GPU, as well as 256MB of on-board flash memory (this was to help run a then-recent Dashboard update. Without this internal memory, a hard drive or memory card was required). The power supply was also reduced to 150W in the "Jasper" revision. The power connector on the back of the systems incorporates a "keying" system that will prevent plugging a lower-rated power supply into an older system.

There are several versions of the Xbox 360 power supply. Depending on the Xbox 360 console’s power requirements, the console will need either a 203-watt power supply, a 175-watt power supply, or a 150-watt power supply.

The connector on the end of the power supply is keyed to fit into Xbox 360 consoles with which the power supply is compatible. If the power supply cord will not plug into the Xbox 360 console, make sure that the power supply is the correct kind as you may need a different power supply.

In the pictures you will see the “keying “system that Microsoft uses for their Xbox 360 consoles. Please note each “plug-side” corresponds directly below to match its compatible “console-side” The console-side is basically and inverse of the plug-side.

Also, keep in mind that a 203W power supply will work in a Falcon or Jasper console and a 175W will work in Jasper. However, none of these work in the opposite way, so a 175W power supply will not work with a Xenon or Zephyr console and a 150W will not work in a Falcon, Opus, Zephyr, or Xenon.