Fast Boot/Fast Startup & Safe/Secure Boot Explained

  • ~~~~~~~ "A Short/Brief Explanation" ~~~~~~~
    "What is, Safe/Secure Boot, Fast Boot & Fast Startup"
  • Safe/Secure Boot: Preforms Hardware Security checks.

  • Fast Boot/Startup: Stores "Last State" instance's, On Startup, Booting back to Last State ( like hibernation).

  • Fast Boot: Can be accessed via BIOS/UEFI,

  • Fast Startup: Can be accessed via the Operating System.


  • "Fast Boot" & "Fast Startup", Are nearly the same. (Explained below).

  • "Safe Boot" & "Secure Boot" Are the same.

Safe/Secure Boot:

  • Safe/Secure Boot is a security process of the BIOS/UEFI to prevent malicious code's, from being run at boot time.(by checking signatures for registered & forbidden components, against a database).
    To check that they (boot manager/kernel/initramfs) are Not tampered with.

Fast Boot:

  • Fast Boot, disables/bypasses a lot of Hardware systems configuration checks (New hardware/etc), & boots from the saved (last state, Like hibernate),File on the disk/partition & in ROM.
    To speed up the bootup time, (Only by 3-5 Seconds)

  • When the computer is shutdown, Windows locks the hard disk/partition.
    With dual boot you will not be able to access that drive from other operating systems.
    Also , If you boot into another OS and then access or change anything on the hard disk/partition that the hibernating Windows installation uses.
    It can cause corruption.

Ultra Fast Boot.

  • A slightly advanced feature, That does the same as Fast boot, & also bypasses the Post Screen, ( logo & BIOS access)


  • This means, if you need to get into the BIOS/UEFI, there are ways to do this & may depend on the motherboard manufacture.

Method to enter BIOS/UEFI with Ultra Fast boot disabled

  1. If you have windows running, Hold down the "Left Shift" Key, while selecting "restart", This will boot to the BIOS/UEFI.

  2. Hold down the F2 Key, while Starting the pc. This will boot into the BIOS/UEFI.

  3. If all else fails some motherboards have a button the reset the BIOS/UEFI or you need to remove the CMOS battery, this will reset the BIOS/UEFI allowing you access again.

With Fast Boot, "Enabled"

  1. It will use a cache file to save your last state (this file will increase to as much as your RAM capacity over time)

  2. It will disable booting from any, optical/network or removable devices.

  3. It Disables "Wake-On LAN".

  4. Windows locks the Hard disk/partition

"When Dual Booting"

  • It’s best "Not" to use "Fast Boot/Startup" or "Hibernation", for dual boot systems.

  • You "Do Not" need to "Disable", "Safe/secure Boot" for dual booting on most of the modern distros.

-: ~~~ "Summary" ~~~~ :-

"Dual Booting":

  • Set, "Fast/Startup Boot", to "Disabled".
  • Leave, "Safe/Secure Boot", "Enabled".

For a Clean Installation,

  • Enable-Both, "Safe/secure Boot" & "Fast/Startup Boot"

  • Leave Safe Boot,"Enabled".
    (Some Distro's (Not many), Will need a workaround). This rarely happens.

  • Before installing:
    Keep Safe/Secure boot "Enabled".
    That will add SHIM-keys to your BIOS/UEFI, and you'll be able to dual boot with Safe/secure boot "Enabled".
    If Safe/Secure Boot was "Disabled" before and you "Enable" it later, Sometimes GRUB may not load (can be fixed temporarily by disabling Safe/Secure Boot again).
    A permanent fix is, editing the BIOS/UEFI.

How to Disable "Fast Boot/Startup

How to Disable "Safe/Secure Boot"

Additional Note:

With a Clean Install. (On Machines with hibernation)
You can only use "Fast Startup", If you have hibernation "Enabled".


Good guide, only I don't feel comfortable replacing a CMOS battery. Last time I did that, my old PC turned unbootable.


I just recently replaced a CMOS battery in a device where the battery was under the mother board and I had to completely strip down the unit to get to it .... first time I ever experienced that ..... desktops are much much easier as you just remove the side panel .... usually just 2 screws .... and the battery is starring you right in the face .... 15 mins as appose to 1 1/2 hours ..... :grinning:

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Laptop batteries are usually in more difficult locations for security reasons. If you ever used the bios authentication (user can mount and read a hard disk but admin to change bios settings or password required for both mount and read as well as bios settings) you would recognize the need for physical "security". By making it an hour and a half job it would be unreasonable to attempt it (onsite anyway). Removing the cmos battery is the only loophole in bios security measures (as long as usb boot is disabled). Although the bios password does include usb booting on newer mobos.

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