On Windows 10 and 11, pressing “Shut down” doesn't always turn your PC completely off. If Fast Startup is on (it is by default on many PCs), here's what shutdown does: Windows closes all your apps, signs you out, and then saves the current state of the Windows kernel to the drive. At the next power-on, it reads that state straight back, which is why startup is quicker.
The kernel is the deepest part of Windows. It manages the hardware and every program. With Fast Startup on, the kernel doesn't start over from the beginning, so some odd problems can still be there after you shut down and turn the PC back on. Pressing Restart is what makes the kernel truly start over.
Below: what Fast Startup actually saves, how it differs from sleep and hibernate, how to turn it off, and a one-line command for a full shutdown just this once.
What does Fast Startup actually save? Not your apps
Microsoft's documentation for driver developers lists the steps clearly. (Drivers are small programs that let Windows control hardware such as the graphics card and network card.)
- Windows shuts down the way it normally would: every app closed, every user signed out. At this point your apps are all closed, but the Windows kernel is still running.
- Windows tells all the drivers to get ready to hibernate.
- Windows saves what the kernel has in memory (including the drivers it has loaded) to the hibernation file on the drive, hiberfil.sys, and powers off.
At the next power-on, Windows doesn't load the kernel from the beginning. It reads the hibernation file straight back into memory. Microsoft says this is much quicker than a traditional start from scratch.
Notice step 1: your apps are closed, not saved. That's the big difference from hibernate.
How is it different from sleep and hibernate?
In short: sleep and hibernate keep the apps and files you were using. Fast Startup keeps only Windows' own kernel.
| Action | Your apps and unsaved files | Windows kernel | Power | Next start |
|---|---|---|---|---|
| Shut down (Fast Startup on) | All closed, signed out | Saved to the hibernation file, read back next time | Off | Quicker than a full start |
| Shut down (Fast Startup off) | All closed | Closed too, loaded from the beginning next time | Off | Full start, slower |
| Restart | All closed | Closed, then loaded again from the beginning | Off, then straight back on | Full start |
| Sleep | Stays in memory | Stays in memory | Only the memory gets power; uses very little | Usually wakes when you press a key or move the mouse |
| Hibernate | Everything in memory is saved to the drive | Saved to the drive too | Off; uses about as little as being shut down | Starts like a power-on, then reads everything back; your apps return as they were; slower than sleep |
Which programs keep running when you lock, sign out, sleep or hibernate is covered in Lock vs. Sleep vs. Sign Out in Windows 10 & 11. For how to set up sleep, see the complete Windows sleep settings guide. On many newer laptops, sleep is Modern Standby (the PC looks asleep, but part of it is still running), which is a different thing: here's how it works.
Why is “Restart” the true fresh start?
Because that's how Microsoft designed it. Microsoft's Windows 8 team wrote it plainly on their official blog: when you choose Restart from the Start menu, Windows does a full shutdown and then starts from the beginning. Fast Startup only affects Shut down, not Restart. The shutdown settings page in Control Panel says so too: restart isn't affected.
So “shut down, then turn it back on” and “Restart” look alike, but they aren't the same. When your PC acts strangely, for example a device stops responding or a system feature running in the background gets stuck, press Restart first.
But if you need to open the case to add or replace hardware, Restart won't do, because it turns the PC back on by itself. What you need is a full shutdown that stays off. That's Microsoft's own example, and how to do it is covered in "I just want one full shutdown. What do I do?"
When does Fast Startup cause problems?
- The problem is still there after you shut down and turn the PC back on. The kernel was read back from the hibernation file, not loaded from the beginning. Drivers do set up the hardware again, but a bad state inside the kernel may come back with it. Press Restart first.
- Your PC has two operating systems, and in Linux the Windows drive can be read but not changed. To read and write Windows drives, Linux uses a program called ntfs-3g. Its documentation is direct about it: before starting Linux, Windows has to be fully shut down, with hibernation and Fast Startup turned off. Otherwise, the Windows parts of the internal drive are set to “read-only” in Linux, which means you can open files but not change or save them. (That's Linux-side documentation, not Microsoft's.)
- You need to open the case and swap hardware. That's Microsoft's own example of when to do a full shutdown.
- A Windows update doesn't seem to have finished. Some people say Fast Startup causes this, but we couldn't find that in Microsoft's documentation, so we can't be sure. Either way, for an update that needs a restart to finish, pressing Restart is the safest choice.
How do I turn Fast Startup off?
Fast Startup is one switch for the whole PC. Turn it off, and Shut down goes back to the traditional full shutdown.
- Open Control Panel and go to Power Options. If you can't find Control Panel, type “Control Panel” into the search box on the taskbar.
- Click Choose what the power buttons do on the left.
- If the options below are grey and can't be ticked, click Change settings that are currently unavailable at the top first.
- Under Shutdown settings, clear Turn on fast startup (recommended), then click Save changes.
If you can't find the fast startup option, hibernation itself is usually off, because Fast Startup needs the hibernation file to work. Open Command Prompt as an administrator: type cmd into the search box on the taskbar, right-click Command Prompt, and choose Run as administrator. Then type powercfg /hibernate on to turn hibernation on. To see which kinds of sleep your PC can use right now, type powercfg /a.
The other way is to turn hibernation off completely: type powercfg /hibernate off (also as an administrator). Microsoft says this disables hibernation completely, and Fast Startup and hybrid sleep stop working too. (Hybrid sleep is a kind of sleep that also saves a copy of your work to the drive.) The price is that you can't use hibernate any more either.
I just want one full shutdown. What do I do?
If you only want Windows to start over once, press Restart. But if what you want is “off, and stays off” (for example, before opening the case), Restart won't do, because it turns the PC back on. You have two options: turn Fast Startup off (see "How do I turn Fast Startup off?"), or use this command:
shutdown /s /full /t 0
/s means shut down, /t 0 means in zero seconds, and /full means a full shutdown. This form comes from Microsoft's Windows 8 team blog. But Microsoft's current documentation for the shutdown command doesn't list /full, and when we typed shutdown /? on Windows 11, we only saw /hybrid, not /full. So we can't promise this command works on every version of Windows. If you want to be sure, turning Fast Startup off is the most reliable way.
The opposite is shutdown /s /hybrid, which Microsoft's documentation describes as shutting down and preparing for fast startup. It has to be used together with /s.
FAQ
Does Fast Startup save the apps I had open?
No. Before a Fast Startup shutdown, Windows closes every app and signs every user out. Only the Windows kernel and drivers are saved. If you want your apps back as they were at the next start, use hibernate.
How much slower is startup with Fast Startup off?
A bit slower, and how much depends on your PC. Microsoft's documentation doesn't give a fixed number.
Does powercfg /hibernate off turn Fast Startup off too?
Yes. Microsoft says it disables hibernation completely, and Fast Startup and hybrid sleep stop working too. The price is that you can't use hibernate any more.
How can I tell if my PC is using Fast Startup?
Go to Control Panel > Power Options > Choose what the power buttons do, and see whether Turn on fast startup (recommended) is ticked. Also, with Fast Startup on, the Windows kernel doesn't start over at every shutdown, so the uptime on Task Manager's Performance tab can keep counting up across several shutdowns. That's our inference from Microsoft's documentation; the documentation doesn't say it outright.
Is PowerDoze's scheduled shutdown a full shutdown or a Fast Startup one?
PowerDoze's Smart Tasks (included in the free version) can shut your PC down at a set time or when a countdown ends. We didn't invent our own way to shut down: PowerDoze uses Windows' built-in shutdown command, shutdown.exe. Shut down uses /s /t 5 /f and Restart uses /r /t 5 /f. Neither adds /hybrid.
Going by how /hybrid is described (it goes with /s and means “prepare for fast startup”), /s on its own should be an ordinary shutdown that doesn't ask for Fast Startup. But Microsoft doesn't say so outright, and we haven't checked it on a real PC yet, so we won't promise it here. To be sure every scheduled shutdown is a full one, turn Fast Startup off.
One more thing: /f force-closes any app that's still open, so unsaved files may be lost. About 30 seconds before a task runs, PowerDoze shows a notification to warn you. If what you want to schedule is sleep rather than shutdown, see Does Windows 10 & 11 have a sleep timer?
You may not need to change anything
If your PC hasn't had any odd problems and you don't have two operating systems, just leave Fast Startup on. Its job is to make startup quicker. You don't have to turn it off, and you don't need any software for this. You don't need us.
A few more things to be upfront about:
- What this post says about how it works comes from Microsoft's documentation going back to Windows 8. Details may have changed between versions, and we haven't tested every version.
- We couldn't find an official answer on whether Fast Startup is behind updates that don't finish.
- This post is about shutdowns that don't turn the PC completely off. If your problem is the opposite, a PC that won't sleep when it should, see Windows Won't Go to Sleep? How to Find and Fix What's Blocking It.
If you'd like your PC to shut itself down at a set time without typing a command every time, give PowerDoze's Smart Tasks a try.
