a method and system of operating a power - managed computer system monitors the life cycle of a hard disk drive attached to the computer system and extends the life span of the hard disk drive by reducing the rate at which hard disk drive spin - up cycles are initiated when the hard drive reaches a predetermined stage it life cycle . software routines which activate or spin - up the hard drive are extended in capability to read the hard drive serial number and record the serial number in a non - volatile memory in conjunction with an incrementing counter . the incrementing counter counts the number of times the hard drive has been activated from the time of installation of the hard drive . the count of spin - up occurrences is indicative of the operating age of the disk drive . a plurality of age levels are defined , for example medium , old and ancient levels so that , when the hard drive spin - up count reaches one of the defined levels , the power management system changes the operation of the hard drive power management .