ASUS B450 boards apparently support PCIe 4.0 now

Discussion in 'Processors and motherboards AMD' started by NEP6XSBW, Jan 27, 2021.

  1. NEP6XSBW

    NEP6XSBW Active Member

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  2. big ROBOT bill

    big ROBOT bill Master Guru

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    Can confirm, although I wasn't aware it wasn't

    B450-cpuz.jpg

    It seems that PCI-E 4 gives a bit more speed, my shiny new 3060 supports 4 I see. It arrives tomorrow so I am a happy puppy :)
     
    Last edited: Jan 27, 2021
  3. Astyanax

    Astyanax Ancient Guru

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    oh boy... asus breaking b450's again.
     
  4. NEP6XSBW

    NEP6XSBW Active Member

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    Try it out when you get it tomorrow and report back how it runs in 4.0 mode.

    Do you happen to have a PCIe 4.0 NVMe SSD, by any chance?
     

  5. Ener

    Ener New Member

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    Its probably just a CPU-Z bug or it's just reporting what the processor supports. It shows pcie 4.0 on my abandoned x370 crosshair VI motherboard too.
     
    Last edited: Jan 27, 2021
  6. big ROBOT bill

    big ROBOT bill Master Guru

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    Is pci4 ram much faster
    a Crucial CT256MX100ssd1
     
  7. NEP6XSBW

    NEP6XSBW Active Member

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    Possibly.

    However, that motherboard did receive a BIOS update late last year.

    Also, there was someone back in 2019 who discovered PCIe 4.0 support on their x370:

    https://www.reddit.com/r/Amd/comments/cdw9zo/pcie_gen4_on_gigabyte_x370_f41b_bios/
     
  8. NEP6XSBW

    NEP6XSBW Active Member

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    That's a SATA SSD.

    You should run a 3DMark test when you get your 3060 to see if you're really getting PCIe 4.0 bandwidth.
     
  9. big ROBOT bill

    big ROBOT bill Master Guru

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    Where can I see if it has?
     
  10. NEP6XSBW

    NEP6XSBW Active Member

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    You can try the 3DMark PCIe feature test, or just see what GPU-Z reports.
     

  11. CyberSparky

    CyberSparky Member Guru

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    CPU-z bug apparently.

    [​IMG]
     
  12. bobblunderton

    bobblunderton Master Guru

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    Users on 300/400 series chip set boards:
    If you find out you are linking @ pci-e 4.0 to either a SSD or your video board...
    You need to check your Windows logs under Administrative tools or whatever the heck it's called (it's been a little bit), and make sure you aren't getting unrecoverable errors on the PCI-E 4.0 bus. It will show it via the logs periodically. If you aren't getting instability of any sort you may be safe to ignore it, but if you are, enter your BIOS and set PCI-E 3.0 negotiation as max link negotiation speed.
    The 400 series was originally to support PCI-E 4.0 with the 3000 and beyond processors. However, due either to an oversight or just not knowing how feeble the PCI-E 4.0 signal is VS PCI-E 3.0, the signal integrity can be compromised on some boards on some ports, some boards on all ports, or some boards on NO ports (meaning: 100% fine). There will end up being too much jitter (imprecision) in the signal if you try to run it too far on a board not designed around the final version of the PCI-E 4.0 protocol, where and when it was known how many re-drivers and such it would need every so-often to ensure signal integrity.
    This, in a nutshell (not having enough redrivers, parallel ground wires and such), is why some intel 400-series boards (not AMD as I was speaking in the above paragraph) won't always support PCI-E 4.0 while others may support it fine.
    Consult updated board documentation, and browse forums, and check change-logs on (all!) BIOS revisions to nail down if you've got none/unsupported/good/great/complete PCI-E 4.0 capability still on your board, and what BIOS revision will be needed to enable it. If it was enabled in one BIOS revision and then later disabled, it's likely it wasn't rock solid so you should not use it even if you have a BIOS version that does. There is nothing PCI-E 4.0 will provide you that will be worth random instabilities that you may incur with a non-500 series chip set + PCI-E 4.0.

    Some boards will fare better than others, and it's possible what is hooked up to PCI-E 4.0 can change how well it works or doesn't work.
    NO 300 or 400 series boards will be able to have PCI-E 4.0 on the south end of the board, due to the chip set link being PCI-E 2.0 x4. B550 chip set link is PCI-E 3.0 x4 and X570 is 4.0 x4.

    PCI-E 2.0 signal can go on average 12~18 linear feet before needing re-drivers or a powered hub/bridge chip of some sort.
    PCI-E 3.0 signal can go 1~3 feet on overage before needing re-drivers or a powered hub/bridge chip of some sort*.
    PCI-E 3.0 signal can go 'about 0.5 feet' on average before needing re-drivers or a powered hub/bridge chip of some sort.

    *I am a bit foggy on the PCI-E 3.0 distance, but suffice to say it doesn't go nearly as far as 2.0 did.
    I think Linus did a video on it, which you should watch IF you can stand him saying 'like' in every sentence as a valley girl in the 80's would be expected to do. Personally though, I'll pass, that guy takes me back to high school and middle school in the 90's when I used to pick on and beat up kids that acted like that. I wasn't a model school child, and hence have to pass on his or Buildzoid's videos...

    Good luck on it and let us know if it works, if it doesn't work, or if it explodes leaving you covered in black soot with your hair blown straight back like a cartoon.
     

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  13. CyberSparky

    CyberSparky Member Guru

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    My motherboard is set to 3.0 standard manually. I always set this manually. I believe it is a bug with CPU-Z.
     
  14. blunden

    blunden Master Guru

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    I just noticed this as well on my X370 when looking at CPU-Z for other reasons. My guess is that it's reading the PCI-E bus specification from the IO die in the CPU, not what the actual motherboard allows. Perhaps it's a change that was made so that B550 would show PCI-E 4.0 even though the chipset itself is PCI-E 3.0.
     

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