A computer comprises: a central processing unit (CPU) driving an operating system (OS); a television (TV) receiver part for receiving external television signals; a storage unit for storing the television signals therein; a reserve-recording set-up part for setting up reserve-recording conditions for the television signals; a record-controlling part for storing the television signals in the storage unit according to the set-up reserve-recording conditions; and a power control part for controlling power supply to allow switching between a normal mode and a power saving mode, and for switching from the power saving mode to the normal mode according to the set-up reserve-recording conditions when a time set-up for reserve-recording approaches, wherein the computer system supplies power to the central processing unit in the normal mode, whereas it does not supply power to the central processing unit in the power saving mode. The computer is automatically supplied with power to initiate the reserve-recording of a television program when the computer is in the power saving mode of the central processing unit, thereby minimizing power consumption due to reserve-recording.