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Install a second OS in dual boot on UEFI BIOS

randall Posted messages 531 Registration date   Status Member Last intervention   -  
Malekal_morte- Posted messages 178136 Registration date   Status Moderator, Security Contributor Last intervention   -
Hello,

On an ASUS PC with UEFI BIOS, I plan to install Windows 10 alongside Windows 8.1.
I've read tutorials online regarding the procedure, which is to disable secure boot and set launch CSM to enabled. I have a few questions that concern me.

First question: upon reboot, I assume I will have the choice of booting like in the old BIOS.

Second question: It’s not mentioned if I need to set secure boot back to enabled and launch CSM to disable as it was originally.

Third question: If I were to install Windows 10 on a second hard drive, how should I proceed and in that case, how do I choose which OS to boot?

Thank you for the response.

Configuration: Windows / Firefox 58.0

2 answers

  1.
    Malekal_morte- Posted messages 178136 Registration date   Status Moderator, Security Contributor Last intervention   24 712
     
    Hello,

    I have read in some online tutorials the procedure which is to disable secure boot and enable the Launch CSM option. I have a few questions that concern me.

    Well no... if you enable CSM, you switch to Legacy BIOS mode and no longer UEFI.
    Don't touch the BIOS...
    Read: https://www.malekal.com/faq-sur-efi-mbr-gpt/

    To have a UEFI installation, your hard drive needs to be in GPT.

    ~~

    For Dual-Boot information, read: https://www.malekal.com/installer-ubuntu-20-04-dual-boot-windows-10/

    ~~

    Basically, you need to install Windows 8 and choose on which partition and therefore hard drive you want to install it.

    Follow this tutorial that explains how to install Windows 8: how to install Windows 8.
    All steps are provided from A to Z with tips at the end to secure Windows 8.

    The steps are roughly:

    - Download the Windows 8 installation ISO: https://www.microsoft.com/fr-fr/software-download/windows8
    - Prepare an installation medium on USB stick or DVD.
    - Boot from it by changing the boot sequence and indicating the USB stick or DVD: How to boot computer from USB stick
    - Follow the prompts to install Windows 8.
    - During the partition phase, select the system partition and format it.
    - Proceed with the installation on this system partition.
    - Select the main partition and install Windows on it.

    ~~

    Third question: If I were to install W10 on a second hard drive, how should I go about it and in this case, how to choose which OS we want to boot?

    An entry will be created and you will have the choice at startup of which Windows to boot.

    --
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