A method and apparatus for converting a signal from a first voltage level to a second voltage level before providing the signal to a processor. A circuit board includes an interface for coupling the circuit board to a peripheral subsystem via a socket. The circuit board also includes a processor that receives signals of a first voltage level, a first signal line, and a second signal line. The first signal line is coupled to the interface and provides a reference signal to the peripheral subsystem that indicates the first voltage level. The second signal line is also coupled to the interface and provides a subsystem signal back from the peripheral subsystem after the signal has been converted to the first voltage level.