Fast startup is a feature first implemented in Windows 8 as Fast Boot and carried over to Windows 10 that allows your PC to start up more quickly, hence its name. While this handy feature can shave valuable seconds from your PC's boot time by saving the operating system's state to a hibernation file, Fast startup may not always work perfectly, prompting many to disable it when they get their hands on a new PC.
Let's take a look at exactly how fast startup works, why you might want to enable or disable it, and how to do so.
What is fast startup?
Windows PCs typically operate in a number of Advanced Configuration and Power Interface (ACPI) power states. An S0 power state, for example, is when your PC is running and ready to respond to your input. There are a number of sleep states, including S1, S2, and S3, and there's also a hybrid sleep state where hibernation is used in tandem with a sleep state.
Hibernation is considered an S4 power state. While hibernating, your PC will seem like it's completely off, but there will be a saved hibernation file ready to be used to boot back to where you were during your last user session. Some power is usually still routed to peripherals so that you can, say, tap your keyboard and have the PC boot.
An S5 power state (soft off) is when your PC is shut down and rebooted completely. There's no hibernation file and no saved user session. There is also a G3 power state, which is when your PC consumes absolutely no power and is completely turned off.
With fast startup enabled, choosing to shut down your PC might look like you're completely shutting things down, but in reality, your PC is entering a mix between a shutdown and hibernation. A hibernation file is indeed used, although it is smaller than usual. Why? You're logged off before the file is created, meaning your session is not recorded. The speed boost comes from the Windows kernel being saved on your hard drive and loaded when booting.
Is your PC truly shutting down?
While fast startup is a pretty harmless tool that can deliver a considerable startup speed boost, especially to PCs using hard-disk drives (HDD), some people prefer to have their PC truly shut down when they click the "Shut down" button on their PC.
In a post on the PC Master Race subreddit, a user pointed out that fast startup was re-enabled in a Windows 10 update following the release of the Fall Creators Update. Following the April 2018 Windows 10 update, Fast Startup was again re-enabled on my own PC, and it seems to have kicked in again following the May 2019 Update.
If you're among the group of people who disable fast startup on their Windows 10 PC, you might want to recheck the settings to see if it's still off.
Why disable fast startup?
Leaving fast startup enabled shouldn't harm anything on your PC — it's a feature built into Windows — but there are a few reasons why you might want to nevertheless disable it.
One of the major reasons is if you're using Wake-on-LAN, which will likely have problems when your PC is shut down with fast startup enabled. Others would like to save the hard drive space that is usually taken up with the hibernation file, and Linux users will likely see complications with dual boot and virtualization. Furthermore, some users have even reported that power buttons on their keyboard will not work and fans in their PCs will continue spinning. These problems are by no means across the board, but they can prove to be frustrating. Finally, Windows 10 updates might not install properly if you have fast startup enabled.
And by not fully shutting down the system, fast startup can also interfere with some system updates that require a full shutdown. If you have fast startup enabled, a potential workaround would be to apply the updates by restarting, rather than shutting down, the system.
Your reason for disabling fast startup might simply have to do with wanting to see your PC truly shut down when you choose to shut down, especially when working with a speedy solid-state drive (SSD), or to have the processor (CPU) uptime reset after booting.
How to enable and disable fast startup on Windows 10
If you'd like to see how your PC performs without fast startup enabled, you can disable it in just a few steps:
- Right-click the Start button.
- Click Search.
- Type Control Panel and hit Enter on your keyboard.
- Click Power Options.
- Click Choose what the power buttons do.
- Click Change settings that are currently unavailable.
- Click Turn on fast startup (recommended) so that the checkmark disappears.
- Click Save changes.
If you want to re-enable fast startup at any point, simply repeat the steps so a checkmark appears next to Turn on fast startup.
Changing the size of your hiberation file
Alternatively, if you're more concerned with device storage and not how fast startup may impact your laptop's performance, you can also change the size of the stored hibernation file. Typically, these files can expand to several gigabytes, and you can reclaim this storage by typing in a simple command prompt by limiting how much space is allocated to the file.
By default, the hibernation file size will vary from system to system, but it is configured to take up to 75% of the installed RAM of your system.
To change the hibernation file's storage size to about half of that, you'll want to enter the Command Prompt menu as an Admin by hitting the Windows+X keys.
Once the Command Prompt dialogue appears, type: powercfg /h /type reduced
That will give you a reduced hibernation file size. If you want to reverse your action, you can type powercfg /h /type full
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Cale Hunt is formerly a Senior Editor at Windows Central. He focuses mainly on laptop reviews, news, and accessory coverage. He's been reviewing laptops and accessories full-time since 2016, with hundreds of reviews published for Windows Central. He is an avid PC gamer and multi-platform user, and spends most of his time either tinkering with or writing about tech.