Downgrading BIOS version below CPU support version

Discussion in 'BIOS Mods' started by tckeeper, Jun 1, 2017.

  1. tckeeper

    tckeeper MDL Novice

    Jun 1, 2017
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    My brother asked me that question, but I can't answer it.

    Scenario:

    1. A motherboard with BIOS version e.g. 1201
    2. A CPU that is supported since version e.g. 0901
    3. A modified BIOS version e.g. 0701

    I assume at 3. it makes no difference if the BIOS is modified or not.

    Procedure:

    - Flash BIOS 0701
    - Update BIOS to 1201


    Resume:

    Is it possible to flash a lower BIOS version than that required by a specific CPU without making the MoBo unusable?
     
  2. MrMagic

    MrMagic MDL Guru

    Feb 13, 2012
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    It probably won't even POST with a BIOS revision below that needed to support the CPU

    But more to the point, if you are flashing back to 1201 after that anyway, why? Nothing from 0701 will remain
     
  3. tckeeper

    tckeeper MDL Novice

    Jun 1, 2017
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    The 0701 BIOS adds a permanent SLIC 2.1 table. (I was told, that it is the main function of this BIOS to do that)

    I feared that it will not POST.
     
  4. Tito

    Tito Super Mod / Adviser
    Staff Member

    Nov 30, 2009
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    @tckeeper

    You're talking about Asus mobos - that permanent SLIC will remain irrespective of down/upgrade.
     
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  5. tckeeper

    tckeeper MDL Novice

    Jun 1, 2017
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    Yes ASUS brand. Sorry, I left it out in the first post.
    It was my hope that it remains after an upgrade, but that doesn't help if the downgrade prevents the board from passing POST since I must be able to enter the BIOS configuration to (re-)upgrade the BIOS and I assume it must pass POST as well if I alternatively want to flash from DOS.
     
  6. Tito

    Tito Super Mod / Adviser
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  7. tckeeper

    tckeeper MDL Novice

    Jun 1, 2017
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    #7 tckeeper, Jun 1, 2017
    Last edited: Jun 1, 2017
    (OP)
    @Tito

    Thank you, I will see if this board supports USB BIOS FLASHBACK.

    I'm currently browsing the request thread, might be a matching BIOS of higher version already exists.

    I discoverd this forum only a few hours ago, so I first need to get a feeling where things are :)

    Update:

    Solved. I found a higher version BIOS and user Serg008 kindly fixed the link for me.

    Thank you MrMagic & Tito for your help and for pointing me the right direction.