ARCHIVED: Is it safe to leave my computer on all the time?

For all practical purposes, it is fine for you to leave your computer on. In fact, for many desktop computers in Indiana University offices, crucial security scans and updates to your operating system and antivirus software are scheduled to take place during hours when you are not at work, so it's important for the computer to be powered on for these scans and updates. You should check with your local support provider (LSP) before turning off an office computer at IU.

Following is further information about keeping your computer powered on:

• Powering on a computer causes changes in temperature as well as voltage spikes, both of which can potentially hurt the circuitry. Although thermal expansions and voltage spikes are designed for and expected, they do cause physical wear. Leaving a computer on reduces such wear caused by repeated on/off cycles.
• A computer's hard disk spins at 5,400rpm or higher, with 7,200rpm drives being common and 15,000rpm drives now available. While a computer is on, its bearings experience wear. On the other hand, modern hard drives generally have "Mean Time Between Failure" ratings of 100,000 to 250,000 hours of uninterrupted operation.

  Computer hardware development is mainly driven by high performance computing, with most innovation directed toward servers, which are designed to run continuously (in order to provide 24/7 availability for services such as email, for example). As such advances in technology have trickled down to personal computers, most could easily run for a decade or more. The average computer will become obsolete long before it wears out.

• Fans on the CPU, power supply, and often the video card can consume quite a bit of power, but use of power-saving modes can considerably lower a computer's power consumption. Many new EPA "Energy Star" compliant computers can place the monitor and hard disk (if not the CPU and motherboard) into a "sleep" mode, resulting in less power consumption while maintaining the ability to respond nearly immediately, without circuit damage.
• Older CRT monitors consume a large amount of power and also produce heat; in fact, an older CRT monitor in a small room can noticeably raise the temperature. This leads to wear and tear, as well as higher cooling bills in the summer. Newer flat panel/LCD monitors, however, generally consume a third as much power, if that. If you do leave your computer on, consider turning your monitor off if you will not be using it for an hour or more; turning the monitor on and off throughout the day is not as wearing as doing so to the entire computer.
• Older monitors can get "burned in" images of whatever appears on the screen for a long period of time. Screensavers were developed in order to minimize part of the screen's exposure to a continuous signal. Modern CRTs are far more impervious to this issue, though, and the problem is completely eliminated in flat panel LCD monitors. Burn-in is not a practical concern unless you have a much older monitor.
• If you leave your computer on, be sure it's plugged into a surge protector to protect against spikes and surges on your power line.
• If your computer is easily accessible to others, be sure to lock it whenever you leave it on; see ARCHIVED: In Windows, how do I lock my workstation without logging off?