A computer includes a CPU and a system unit, and further includes a power source which generates source power, a system driving power generator which converts the source power to system power and which provides power to the system unit, a CPU driving power generator which outputs driving power to drive the CPU, and a controller which selectively supplies the source power or the system power to an input terminal of the CPU driving power generator according to an operation mode of the CPU. Thus, a computer adjusts a level of power supplied to a CPU driving power generator according to a CPU mode and improves power efficiency, and includes a control method thereof.