F8 Safe Boot seems to have vanished from Windows 8? One of the strange quirks of Windows 8 is that the Boot into Safe mode by pressing F8 at boot time has been disabled. Microsoft justifies this by saying that modern computers boot too fast.
The response window for pressing the F8 key on a Windows 8 SSD-based UEFI system is less than 200 milliseconds. This is surely okay for modern Windows 8 devices, but for the rest of us folks out there with slower machines (or for those who prefer the F8 Safe Boot method because it is familiar to us), we want the F8 Safe Boot key back.
Bring Back F8 Safe Boot
Luckily for us, Microsoft has made this possible by following the steps below. From inside Windows 8, press Windows Key +X to bring up the WinX menu.
From this menu, select the Command Prompt with Administrator rights. If the UAC pops up, respond appropriately.
In the command prompt, type the following command and press Enter.
bcdedit /set {default} bootmenupolicy legacy
A confirmation will be displayed on the screen. The boot menu policy for your Windows 8 machine is now set back to the way it was in Windows 7. From now on, when you boot your Windows 8 PC and see the blue windows flag appear on the screen for the first time, you can access the advanced boot options by pressing and holding down the F8 Safe Boot key.
If you decide that you want to set the boot menu policy back to the way it was in Windows 8, run this command from the Command Prompt.
bcdedit /set {default} bootmenupolicy standard
Method 2: F8 Safe Boot
There is a second method (which actually has nothing to do with the F8 key) to boot Windows 8 into Safe Mode. Press Windows Key+R to display the Run dialogue and type msconfig. This will display the System Configuration screen.
In the System Configuration screen, select the Boot tab to access the Boot Options. From here you can select Safe Boot. When you click OK, Windows 8 will prompt you to restart. When you do, Windows 8 will boot straight into Safe Mode with the option you selected in the System Configuration.
Reference: TechRepublic