RF Board
The RF Board is a small PCB that plugs into the front of the motherboard. It is responsible for wireless controller connection and the front panel buttons/LEDs.
On the Xbox 360 E, it contains the power button, eject button, and sync button, and is split into 2 PCBs which are connected by a ribbon.
Original Xbox 360
The RF board on the Original Xbox 360 contains the power button and Ring-Of-Light LEDs.
RF01
Codename Argon. Used on all Original Xbox 360's except for Tonasket.
RF02
Known as xFreedom. Used on Tonasket.
Xbox 360 S
The RF board on the Xbox 360 S has capacitive sensors for the power button and eject button. It also contains the sync button and Ring-Of-Light LEDs.
1409
1410
Xbox 360 E
The RF board on the Xbox 360 E is split into two PCBs, connected by a ribbon cable. The main PCB connected to the motherboard contains the primary functionality. The smaller second PCB - attatched to the faceplate - contains power button, eject button, sync button, and Ring-Of-Light LEDs.