An electronic system having a power efficient differential signal between a first and second electronic unit. A controller uses information, such as compliance with data transmission rate requirement and bit error rate (BER) versus a BER threshold to control power modes such that a minimal amount of power is required. Amplitude of transmission and single ended or differential transmission of data are examples of the power modes. The controller also factors in a failing phase in a differential signal in selecting a minimal power mode that satisfies the transmission rate requirement of the BER threshold.