Do you leave your computer on all the time, or shut it off when it’s not in use; does it really make a difference?

If you’ve been asking yourself this question, then you’ll be happy to hear that you can choose whichever way you want. You just need to understand the ramifications of your choice, and take a few precautions to ensure you get the longest life you can from your computer.

The most important precaution is to  add a UPS (Uninterruptible Power Supply), no matter which method you choose.

A UPS can protect your computer from many of the dangers it’s likely to face.

The Things That Can Harm Your Computer

All of the parts that make up your computer have a limited lifetime.  The processor, RAM, and graphics cards all experience aging caused by, among other things, heat and temperature. Additional failure modes come from the stress of cycling a computer on and off.

But it’s not just your computer’s semiconductors that are affected. Mechanical components, such as the ones in hard drive, optical drives, printers and scanners, are all affected by the power cycling they may undergo when your computer is turned off or on. In many cases, peripherals, such as printers and external drives, may have circuitry that senses when your computer is powered on or off, and initiates the same condition, turning the device on or off as needed.

There are other failure modes to consider that originate externally to your computer.

The one most often mentioned is a power surge and power drop, where there’s a sudden rise or fall in voltage on the electrical circuit that your computer is plugged into. We often associate these surges with transient events, such as nearby lightning strikes, or devices that use a lot of power at once (vacuum cleaner, hair dryer, etc.).

All of these failure types need to be considered. Leaving a computer turned on can reduce exposure to some of the failure types, while turning your computer off can prevent most of the external vectors that can cause the failure of a computer’s components.

When Running 24/7 Which is Better, Sleep or Hibernation?

One possible problem with running your computer 24/7, even if it isn’t actively being used, is that you may discover that your computer entered a hibernation mode that’s extremely similar to turning your computer off and back on again.

Depending on your computer and the OS it’s running, it may support multiple types of power saving options.

Generally speaking, sleep mode is designed to reduce power consumption while keeping the computer in a semi-operational state.

In this mode, your computer spins down any hard drives and optical drives it may have. RAM is powered down to a lower activity state. Displays are usually dimmed, if not outright powered off. Processors run with a reduced clock rate or in a special low-level state. In sleep mode, the computer can usually continue to run some basic tasks, though not as speedily as in a normal state. Most open user apps are still loaded but are in a standby state.

There are exceptions, depending on your OS, but you get the idea. Sleep mode conserves power while keeping the computer turned on.

Hibernation, another version of reducing power consumption, varies a bit between Mac, Windows, and Linux OSes.

In hibernation mode, apps that are running are put into a standby state, and then the content of RAM is copied to your computer’s storage device. At that point, RAM and the storage devices are powered off.

Most peripherals are put into standby mode, including the display. Once all data has been secured, the computer is essentially turned off. Restarting from hibernation mode isn’t much different, at least as experienced by the components that make up your computer, than turning your computer on.

As you can see, if you haven’t ensured that your computer won’t enter its hibernation mode after some amount of time, you’re not really keeping your computer on 24/7. So, you may not be realizing the effect you wanted to achieve by not turning your computer off.

If your intent is to run your computer 24/7 to perform various processing tasks, you’ll want to disable all sleep modes except for display sleep. You probably don’t need the display to be active to run any of the tasks. The method for using only display sleep is different for the various operating systems.

Some OSes have another sleep mode that allows specified tasks to run while placing all remaining tasks in standby mode. In this mode, power is conserved but processes that need to be run are allowed to continue. In the Mac OS, this is known as App Nap. Windows has an equivalent known as Connected Standby, or Modern Standby in Windows 10.

No matter what it’s called, or the OS it runs on, the purpose is to conserve power while allowing some apps to run. In regard to running your computer 24/7, this type of sleep mode doesn’t exhibit the type of power cycling seen in hibernation mode, so it could meet the needs of those who don’t wish to turn their computers off.

Leave the Computer On or Turn It Off: Final Thoughts

If you’re asking if it’s safe to turn your computer on and off as needed, the answer is yes. It’s not something I would worry about until the computer reaches old age.

If you’re asking if it’s safe to leave a computer on 24/7, I would say the answer is also yes, but with a couple of caveats. You need to protect the computer from external stress events, such as voltage surges, lightning strikes, and power outages; you get the idea. Of course, you should be doing this even if you plan to turn the computer on and off, but the risk is slightly greater for computers left on 24/7, only because it’s likely they’ll be turned on when a severe event occurs, such as a summer thunderstorm rolling through your area.