Windows 10: Hybrid (UEFI / MBR) ISO's -- UEFI BOOT (CSM)

Discus and support Hybrid (UEFI / MBR) ISO's -- UEFI BOOT (CSM) in Windows 10 Installation and Upgrade to solve the problem; Hi folks recently I couldn't get some newer iso's from UUPDUMP to boot using RUFUS V 10 to create bootable usb sticks when these isos are HYBRID boot... Discussion in 'Windows 10 Installation and Upgrade' started by jimbo45, May 19, 2020.

  1. jimbo45 Win User

    Hybrid (UEFI / MBR) ISO's -- UEFI BOOT (CSM)

    Hi folks
    recently I couldn't get some newer iso's from UUPDUMP to boot using RUFUS V 10 to create bootable usb sticks when these isos are HYBRID boot (i.e they can boot either MBR or UEFI).

    However changing the BIOS options to enabling UEFI boot (CSM module) as well as UEFI then it all worked OK -- I had CSM disabled previously but hadn't needed it so far.

    Anybody know what this CSM thing is

    It's an older MOBO which can also boot MBR (legacy) but the bios setup has to be entered and changed.

    I don't see any problems on a more modern laptop

    I thought the CSM module was only something to do with UEFI boot for Windows 7 but obviously I'm wrong

    Any gurus here who can explain what it is.


    jimbo45, May 19, 2020

  2. MBR to UEFI conversion

    In addition to the good explanation that Greg provided, I would like to add a technical distinction:

    The UEFI is akin to firmware while the MBR is a partitioning method. So you would compare the UEFI to the BIOS, and the MBR to the GPT. You wouldn't speak of converting MBR to UEFI.

    I said that the UEFI is akin to firmware, because it's not really firmware. The BIOS really is firmware, because it resides on a chip on the motherboard. But the UEFI is programmable software that sits between the computer’s hardware and the operating

    The only compelling reason to convert your hard drive from MBR to GPT is if you need to have more than 4 primary partitions on the drive. MBR is limited to 4 primary partitions. And then, since GPT can't be run from the BIOS, you would need to use the UEFI.

    The UEFI has many technical improvements over the BIOS, to be sure, but considering the uncertainty inherent in converting old hardware, there isn't really a good reason to attempt converting from BIOS to UEFI other than the satisfaction in pulling off a
    complicated maneuver.
    0dcafe6b-10a8-4bc9-b8b2-213ccfc2f28c, May 19, 2020
  3. 3oddbits Win User
    RX480 UEFI GOP Driver


    I did save the OEM / Stock VBIOS to file.
    Did NOT flash the VBIOS.
    Do ya'll want a copy of the OEM / Stock VBIOS uploaded?

    Further Problem info :
    EFI shell lists the UEFI GOP driver as loaded / connected.

    Win 7 x64 Pro won't boot with out CSM Video Legacy set. x2 mode only.
    Win 10 x64 Pro will boot but stays in x2 mode in both CSM Legacy && UEFI mode.
    3oddbits, May 19, 2020
  4. newtekie1 Win User

    Hybrid (UEFI / MBR) ISO's -- UEFI BOOT (CSM)

    Can't disable UEFI boot on HP 250 G3

    He is talking about completely disabling the UEFI boot path, you can not do that on a UEFI BIOS.

    Enabling CSM just adds the legacy boot path, it does not disable the UEFI path. He is not talking about just enabling the legacy path and installing Windows in BIOS mode. He wants to completely disable the UEFI boot path from within the BIOS, you can not do that. Even if Windows and Linux is installed using the legacy path, the UEFI path will still be active.
    newtekie1, May 19, 2020

Hybrid (UEFI / MBR) ISO's -- UEFI BOOT (CSM)

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