Fast Startup can be disabled through the Power Options menu.  To open the Power Options menu, press Win + R to open the Run window and enter powercfg.cpl.

Once in the Power Options menu, select Choose what the power button does from the left side-bar.

In the Shutdown settings section, un-tick the Turn on fast startup (recommended) option and click Save changes.

Turn on fast startup is grayed out

If the Turn on fast startup (recommended) option is not available, click the 🛡Change settings that are currently unavailable link to unlock the additional settings.

Once fast startup is disabled, we recommend doing a cold boot of the PC to ensure the settings are full enabled.

• Shutdown the PC from the Start Menu.
• With the PC shutdown, turn off the Power Supply switch at the back of the PC
• Allow the PC to sit without power for at least 30 seconds.
• Turn on the Power Supply switch, then start the PC.

What is Fast Startup?

Fast Startup, previously known as Hibernation is a feature that allows Windows to dump memory, kernel, and loaded drivers to local storage during a shutdown.  This file is re-loaded when the PC is started again, reducing startup times.

This feature is useful for older systems booting from a mechanical hard drive as well as laptop PCs to conserve battery life.  It is worth noting however that this feature is generally not necessary for Desktop PCs booting from a Solid State Drive, as the fast speeds of a Solid State Drive negate most if not all of the perceived boot speed.