ASUS releases beta bios beta versions with SAM - Resizable BAR function for Intel Z490 motherboards

Discussion in 'Frontpage news' started by Hilbert Hagedoorn, Nov 30, 2020.

  1. Hilbert Hagedoorn

    Hilbert Hagedoorn Don Vito Corleone Staff Member

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  2. asturur

    asturur Maha Guru

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    i wonder if i m gonna see resizabler bar support for x470 and ryzen 2700x, or 3700x
     
  3. Valken

    Valken Ancient Guru

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    Any 6800 or XT users on Intel systems? Does it work?!
     
  4. Sylencer

    Sylencer Member Guru

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    I was wondering why the beta bios for my Formula had no changelog. Will wait to update this once i can get a use out of it.
     

  5. SpajdrEX

    SpajdrEX AMD Vanguard

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    God damn it ... I have Gigabyte mobo :-/
     
  6. gx-x

    gx-x Maha Guru

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    I have "Above 4G decoding" on my Z370 ASRock, if that's the same thing talked about here...

    edit: obviously not, that's not BAR...
     
  7. pharma

    pharma Ancient Guru

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    "Above 4G decoding" is one of the names for Resizable Bar, or RBAR.
     
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  8. gx-x

    gx-x Maha Guru

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    Thanks.
     
  9. SpajdrEX

    SpajdrEX AMD Vanguard

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    Yep, it needs to be two options, above 4G enabling is not enough.
     
  10. gx-x

    gx-x Maha Guru

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    I haven't noticed any difference with it ON/OFF to be honest...
     

  11. pharma

    pharma Ancient Guru

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    You need to wait until Nvidia and Intel support via drivers if you have an Intel MB w Nvidia GPU. If you have a AMD GPU then you need to wait for AMD & Intel driver support.
     
    Last edited: Dec 1, 2020
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  12. pharma

    pharma Ancient Guru

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    Do you have a link? It may be true for AMD motherboards.
    For Intel MB's "Above 4G decoding" one of 4 different names motherboard manufacturers use for Resizable RBAR. It is enough besides driver support.

    Edit: Just saw the image above. Perhaps you do need both for AMD cards.
     
  13. Trihy

    Trihy Member Guru

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    Why they always talk about "exclusive" z490 features?

    This bios is available for other 400 series chipset.

    Like when most webs talk about rocket lake only compatible with z490 boards. It will be probably compatible with the entire 400 series.
     
  14. Astyanax

    Astyanax Ancient Guru

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    no it isn't.
     
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  15. pharma

    pharma Ancient Guru

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    yes it is. Already went over this with you. Google is your friend.

    Reddit post detailing resizable BAR usage for years on Linux enabled via 4G Decoding.
    Smart Access Memory already works on Linux and is not exclusive to Zen 3 or Navi 2x : Amd (reddit.com)
    How to Resolve GPU Memory Mapping Issues in XenServer (citrix.com)
     
    Last edited: Dec 1, 2020

  16. JonasBeckman

    JonasBeckman Ancient Guru

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    Whatever AMD's doing on their boards appear dependent on two separate options one of which is SAM and the other being Above 4G Decoding.
    Not sure how this is implemented on Intel boards though or what the separate SAM option on AMD's boards does if 4G Decoding achieves a similar purpose.

    EDIT: Guess the naming varies a bit on AMD systems too but it's still two separate toggles in the bios and if I understand it correctly also a reliance on UEFI without the compatibility support module. :)
    https://www.amd.com/en/technologies/smart-access-memory

    [​IMG]
     
  17. pharma

    pharma Ancient Guru

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    I'm not sure exactly about the function of the second toggle. It might be related to specific AMD-specific instructions to access gpummu features, but this is speculation from the reddit link above.
     
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  18. SpajdrEX

    SpajdrEX AMD Vanguard

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    So ... anyone with mentioned Asus Z490 motherboard + 6800(XT)? I wan't to know the results :)
     
  19. brogadget

    brogadget Active Member

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    from @RED.Misfit:
    "This is a PCI express feature, everyone with a PCI 3.0 and a compatible motherboard (bios option "resizable BAR" required) should be able to use it.
    Windows is compatible since WDDM v2, so Windows 10 only."
    -> https://docs.microsoft.com/en-us/windows-hardware/drivers/display/resizable-bar-support

    I really don´t know, why AMD is hyping it´s so called SAM feature that much, because it is not an AMD feature, it simply belongs to PCIe3.0 specification and therefore it should be available on all mainboards with enabled in BIOS, no matter if AMD, nvidia or Intel. Your OS must support it as well e.g. see posting and link above from @RED.Misfit

    AMD says approx. 10% performance gain with SAM on, in my eyes with games already over 100fps this is almost nothing (most games only show 5 or maybe 10fps more in reviews with SAM enabled).

    Much more significant is the fact, that "resizable bar" or SAM will work only in UEFI with CSM mode switched OFF, as far as I know. That means, your boot disk must be formatted in a GPT partition scheme. This will cause much more trouble for users, because many systems are still booting with CSM mode ON. So, if you want to use your MBR boot disk (and your DATA) with "SAM" or "resizable bar", you have to repartion it to GPT scheme first.
     
    Last edited: Dec 2, 2020
    -Tj- likes this.
  20. Workzero

    Workzero Member

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    I upgraded my Asus Strix z490-E to the beta version.

    Now the option Rezisable Bar appears but only let me select Disabled or Auto.

    Anyone knows how do i check if is enabled in Windows?
     

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