Can powering off your computer cause it to wear down over time?

The belief that regularly shutting down and restarting a computer leads to wear is mostly a myth, though it has some historical basis. In the early days of personal computers, frequent power cycles could harm the hard disk drive, a rotating magnetized disk read by a 'needle' called the head [source: Nordman].

When a computer is running, the hard drive’s head doesn't touch the spinning disk. Instead, it hovers above the disk on a thin air cushion. In early PCs, the head would rest on the disk's surface when the system was turned off. Upon powering up, the head would briefly remain on the surface as the disk started spinning. This created a risk of scratches and data loss. However, modern computers built after the early 1990s have heads that safely park in a secure area when powered down.

For modern computers, frequently powering them off and on has little impact on their overall lifespan. The reality is that computers are not built to last forever. On average, a PC lasts five to seven years before it encounters hardware failures, software viruses, or becomes outdated by newer technology. Today's PCs can withstand 40,000 on-off cycles before breaking down [source: EnergyStar.gov]. If you power down your computer at night and turn it on in the morning, it could last for another 109 years.

If anything harms your computer, it's leaving it running. Computers generate heat while processing data and running software. This heat can damage internal components and cause the computer's fan to run longer [source: Greenemeier]. The more the fan operates, the quicker its bearings will wear out [source: Gwinn].

The main downside of shutting down and restarting isn't the wear, but the time it takes for the process. Those few seconds—or, heaven forbid, minutes—at the start of the day can feel endless. A smart alternative to shutting down or keeping the computer on is using sleep or hibernate modes. In sleep mode, only the short-term RAM memory remains active. The difference between a sleeping computer and a shut-down one is the small amount of energy it uses—between one and five watts in sleep mode versus zero for a completely powered-down machine [source: Cross]. A sleeping computer doesn’t generate heat, doesn’t activate the hard drive or fan, and is ready to go in seconds.

Experts generally agree that if you won’t be using your computer for several hours—overnight is the most obvious example—shutting it down entirely is a good choice. It won’t cause any major wear, it will save some electricity, and it will give your system a chance to restart fresh the next day.

For more advice on how to extend your PC's lifespan, check out the related links on the next page.