The UEFI BIOS and standard legacy BIOS used in desktop and laptop PCs

Shutting Windows 8.1/10 down completely in order to be able to enter the PC’s BIOS

Note well that Windows 8.1/10 never shuts down completely, it goes into a deep sleep mode similar to hibernation, starting up from where it left off, bypassing the BIOS. The new feature is called fast startup, which is dealt with in the following article.

4 Ways To Speed Up Windows 10 Boot Times –

A UEFI BIOS can behave as a standard BIOS for operating systems that require one, but provides additional functions for an operating system that supports a UEFI BIOS, such as Windows 8.1/10. However, note that a UEFI cannot perform the POST (Power On Self Test) that tests that the hardware is all present and working. There is more information on this under the next heading. A windows 8.1/10 computer with a UEFI BIOS can boot very quickly indeed, especially with a solid-state boot drive (SSD). The following video shows a laptop booting fully in a few seconds.

Microsoft demos fast boot times in Windows 8 –

However, note well that, as with the hibernation mode used by XP, Vista and Win7, you won’t be able boot into the BIOS from the default shutdown by pressing its entry key (Del, F2, etc.). A full shutdown is required because the BIOS isn’t accessed during a fast startup.

Some computer manufacturers provide a way of shutting down completely. For example, Acer’s shutdown icon allows the user to select Sleep, Hibernate, Restart or Shutdown. To shut down all the way, the Shift key is held down while the shutdown icon is clicked. The Shift is held down until the machine powers off completely. You must find out from its user manual if a new Windows 8/8.1 computer provides a similar option.

Fast startup can be disabled via the Shutdown settings in Power Options. On the desktop screen, open the Control Panel, click Hardware and Sound/Power Options/System Settings. At the bottom of the dialog box you can disable “Turn on fast startup”. Now you will be able to enter the BIOS at startup by pressing its entry key.

Page 5 – The UEFI/EFI BIOS