A data storage drive comprises a storage disk, a read/write head, and signal processing circuitry in signal communication with the read/write head. The read/write head is operative to read data from and write data to the storage disk at a plurality of data transfer rates. Moreover, the signal processing circuitry is powered by a variable power source. The variable power source varies supply voltage to the signal processing circuitry as a function of a current one of the data transfer rates of the read/write head. Power consumption is reduced in this manner.