Power management
Fast Startup (HiberbootEnabled) and hibernation
Why 'shut down' does not fully shut down, and when that causes problems
Last updated
Should you disable Fast Startup?
With Fast Startup enabled, shutting down does not fully shut down: Windows closes your session but hibernates the kernel and drivers to disk, then restores that image on next boot. It makes cold boots faster. It also means a shutdown does not clear driver state, which is why a surprising number of hardware problems are fixed by Restart but not by Shut Down.
Registry location and values
HiberbootEnabled
- Location
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Power- Value name
HiberbootEnabled- Type
REG_DWORD- Default
- 1
| Value | What it does |
|---|---|
0 | Fast Startup off. Shutdown performs a full shutdown. |
1 | Fast Startup on. |
What Windows actually does with this
A normal shutdown ends user sessions and then powers off. With Fast Startup, after ending user sessions Windows hibernates the remaining kernel session to hiberfil.sys. Booting reads that file back rather than re-initialising drivers, which is faster than a cold start.
What it affects
Boot time, and whether driver and kernel state is genuinely reset by a shutdown. Also affects dual-boot setups: the Windows filesystem is left in a state other operating systems should not write to.
Is it worth changing?
Worth disabling if you dual-boot, if you are troubleshooting a driver or peripheral problem, or if you have ever been told to restart rather than shut down to fix something. Otherwise it is a genuine boot-time saving with no performance cost once you are at the desktop. It has no effect on frame rate. Note that `powercfg /h off` disables hibernation entirely, which also removes Fast Startup and reclaims the disk space hiberfil.sys occupies -- a larger change than turning off Fast Startup alone.
What can go wrong
Disabling hibernation entirely removes the ability to hibernate and, on laptops, the hibernate-on-critical-battery safety net. Leaving Fast Startup on while dual-booting risks filesystem corruption if another OS writes to the Windows partition.
How to undo it
`powercfg /h on` to restore hibernation, then Control Panel → Power Options → Choose what the power buttons do → tick Turn on fast startup.
Create a System Restore Point before editing the registry. Every setting on this page is reversible, but a restore point is the difference between undoing one change and reinstalling Windows.
Which Windows versions this applies to
Windows 8 and later.
Fast Startup (HiberbootEnabled) and hibernation: common questions
Why does Restart fix things when Shut Down does not?
Because with Fast Startup on, Restart performs a full kernel reinitialisation and Shut Down does not. This is the single most useful thing to know about the feature.
Sources
Does JINSHI Tweaks change this?
This page documents settings that correspond to the following toggles in JINSHI PC Tweaks: Disable Fast Startup, Disable Hibernation.
The reference above is written to be usable without the product. Everything here can be applied by hand for free. What the application adds is that the change is applied in one pass, a System Restore Point is created first, and each toggle can be reversed individually.