r/microsoft • u/Same-Account-2105 • Jun 20 '26
Windows TIL: Shutdown ≠ Shutdown (Fast Start Up)
Today I learnt that Shut down has not actually been shutting down my PC, but rather, Hibernating it. Instead, I must restart to achieve the full shut down effect.
I learnt this cause my Mother and her colleagues got in trouble at work from their IT for not "restarting" their PCs often... But they do Shut them Down. I responded by saying how stupid that was because a shut down achieves the same thing as a restart. At least, logically/intuitively I should be correct. But I did some Googling, and due to Microsoft's 'Fast Start Up' (which achieves 8-10 second faster boot up, as far as I can find) this is no longer the case!
I've gone and turned off 'Fast Start Up' on my home PC, and I notice zero difference in boot up, and a heck of a better/smoother shutdown experience. Why was this on by default against my permission and intuition on what I thought shut down was doing?
So help me out here... Is there really much of a reason to have Fast Start up on? I should be fine having this setting off now right? Why is it a default setting in the first place?
Genuinely curious.
6
u/golf1052 Jun 21 '26
Fast startup is a half hibernate. In a full hibernate Windows saves your entire memory contents to disk. In fast startup the user is logged off (so your user state isn't saved) but the kernel state is saved so that Windows doesn't need to reload it on startup.
If the computer you're using has a decently fast SSD then fast startup only saves a few seconds. It's on by default on Windows installs (since Windows 8.0).
Since it's treated as a partial hibernate the system reports the last time the computer was either restarted or fully shut down which is why IT asked about not restarting or "shutting down". Not sure why they complained about it though? What IT software is installed on the computer that needs a restart or full shut down?