There are a lot, and I really mean a LOT, of myths concerning hardware components, but nothing has attracted more guesses and myths turned into popular knowledge also known as "urban legends" than the hard disk drive did. I mean, how many "did you know..." have you ever heard about USBs? While some of these urban legends are based on at least some grain of truth, there are others that are simply taken from a really bad Sci-Fi novel. Let's see three of the most popular urban legends concerning hard disk drives.
"Formatting a drive is a sure way to kill it." Wrong, so totally wrong. Formatting a drive, or just a portion of it simply means that all data in those areas is erased and a new filesystem of user's choosing is neatly laid out. Because during the formatting process the hard drive doesn't do anything out of the ordinary (it just writes and reads data, just like it usually does), simply formatting a disk will never be the cause of a hardware failure.
"Defragmenting the hard drive will stress the head actuator." This one has a tiny grain of truth in it, even misplaced as it is. Defragmenting a hard drive may involve a lot of seeking as the drive layout is rearranged. However, this is no more and no less stressful to the hard drive's components as a normal, day-to-day operation. While head actuators will work a lot during the defragmentation process, once this is complete the seek time will be much reduced, so the actuators' workload will decrease.
"Power cuts and cheap PSUs slowly kill your hard drive." Power cuts, and we are not talking power cuts followed by an overvoltage spike, cannot damage a hard drive because, as the power fails, the read/write heads are automatically positioned in the parking area, so they will not come crashing on the data surface. A poorly made, cheap PSU doesn't kill your hardware. It can cause general instability and if you are truly unlucky, it may send an overvoltage spike that will instantly fry the logic board of the hard drive or burn the motor. So in either case, it is not slowly, it is so fast you'll never know what hit you.