The Xbox 360 PSU uses a proprietary connector that varies slightly between console generations (Original, S, and E). Despite physical differences, the electrical logic remains consistent.
A signal line. When the console is turned on, it pulls this line high (usually to 5V) to tell the PSU to activate the main 12V rail. Schematics For Xbox 360 Power Supply
A low-current "always-on" rail that powers the console's power button and wireless receivers while in standby mode. The Xbox 360 PSU uses a proprietary connector