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ZDNET’s key takeaways

• Sleep, hibernate, and shut down all behave differently. 
• Newer PCs support “Modern Standby”, a state that’s different from traditional sleep.
• Shutting down your computer may actually be faster than restarting it. 

Have you ever put your laptop in your bag, only to pull it out and find it’s hot and the battery is drained, even though you put it to sleep? Turns out Windows may have gotten in its own way, preventing it from fully going to sleep.

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Modern standby is the sleep state most newer PCs go into when you tell them to sleep. It cuts power to the display and CPU, but allows for minimal background processes to continue, so you can have that instantaneous wake time. This mode might not be the most efficient way to save your battery, however. Here’s the breakdown. 

What’s the difference between Modern Standby and Sleep?

Your PC can be in one of six states, identified by “S” followed by a number. For example, S0 refers to the “Working” state: on, and operating normally. At the other end is S5, which means that it’s powered off. There are a few different states in between, but not all are commonly used.  

“Modern Standby” (S0 Low Power Idle) 

Most newer PCs enter a low-power state, often called “Modern Standby,” when you tell them to sleep. This is like a better-optimized form of sleep that lets your PC quickly switch back to a working state (S0) — similar to how your smartphone wakes up instantaneously.

In this state, the display is off, as are most core components, but there is some very limited background activity so your computer can snap back to work at the touch of a button. In theory, battery life should drop to a trickle. More on that in a moment. 

Sleep (S1, S2, S3)

If your PC doesn’t support Low Power Idle, it will go into the traditional Sleep state (S3). It’s still a low-power state where the screen and main components shut down, and the computer “remembers” your open apps and windows, but it might not snap back as quickly as modern standby. 

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Whether your computer supports modern standby or not, you’ll still see only one “Sleep” option in Windows’ power menu. These states occur in the background, but there’s no consumer-facing differentiation. If you want to see if your computer supports modern standby, simply right-click the Windows start menu, click “Terminal (Admin)”, and type “powercfg /a”.

As for S1 and S2, they are mostly deprecated states that are now redundant with the current sleep settings. 

Hibernate (S4) 

Putting your computer in hibernation is like Sleep, but it goes one step further by completely cutting power to your machine. Upon entering Hibernate, your PC takes a snapshot of the contents of active memory so that it can quickly access it when it starts up again. 

This state is not as commonly used these days, since it’s mostly redundant. As such, it might not even be available on your computer’s start menu. To enable it, go to Control Panel > Hardware and Sound > Power Options, then in “Shutdown Settings” toggle the box next to “Hibernate.”

Restart

This mode clears the computer’s memory, completely resets the OS and all operational processes, and starts from scratch. This is the most thorough way to reset your system.

Shut Down (S5) 

Selecting this option will clear the PC’s memory, terminate all processes in the OS, close all applications, and completely cut power to the machine. However, it’s called a “soft off” because it actually remembers some settings to start up faster, enabled by a feature called “fast boot.”    

Also: How to clear your Windows 11 PC cache (and why you shouldn’t wait to do it)

Fast boot retains functional core processes, so it doesn’t have to go down the checklist and re-initialize all the critical components when it restarts again. It’s like the computer saying, “These are the startup settings that worked last time, so I’m going to remember them.”  

Fast boot is, by and large, safe and shouldn’t require messing with for most users, but there are instances where you might want to turn it off. For example, if there’s a problem with one of the settings or drivers, and your computer doesn’t recognize it, it’ll just keep loading it when you turn your computer back on.

How to turn off fast boot  

If you want to disable fast boot, it’s easy to do in the Control Panel > Hardware and Sound > Power Options and uncheck the box next to “Turn on fast startup”. You can enable it again at any time. 

Another reason to turn off fast boot is if you’re on a company-issued computer that regularly receives scheduled updates, but you don’t have time to restart during working hours. That way, if you shut down the PC at the end of the day, you’ll have a built-in restart every time you turn on your computer in the morning. Just keep in mind it could take longer to start up. 

Additionally, note that this doesn’t affect larger Windows OS updates, which will still require installation and a restart. 

Does modern standby preserve battery? 

Yes, but it may not be the most efficient way. In S0, the CPU enters a deep idle state, and storage is fully gated from power, but background processes can still run in short bursts to enable fast wake times.

Also: How to create a Windows recovery drive in 4 easy steps – before it’s too late 

But more importantly, modern standby relies on firmware and drivers behaving perfectly for it to work properly. In reality, certain devices or apps can be doing something unexpected in the background that straight up prevents the device from entering a true S0 state, even though it might appear to be in one. 

This could be one of the reasons why you pulled a hot laptop out of your bag that you swore was powered down: something prevented it from actually going to sleep, and now your battery just lost 20%. In situations where you really want to save power, selecting the “Shut Down” option is the safest bet, and with fast boot, it starts up faster than you’d expect.