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  1. #1
    New ROGer Array
    Join Date
    Sep 2021

    Crosshair VIII Extreme -BIOS Bootup - PCI_1 Speed was set to 8x

    Hello Community,

    I have a Crosshair VIII Extreme. The PCI-E_1 Speed was first working fine with 16x4.0 Speed. After a few days i bootet up the Pc and the Bootup took longer then usual. Then Before the BIOS ROG Logo Screen the Message appeared "PCI_1 Speed was set to 8x".

    Since that i can not manage to run the Graphics Card to 16x Speed. Even if i set Everything on 3.0, 4.0 or Auto.

    The Settings in the "CPU PCIE Configuration Mode" is set to "PCIEx16_1+M.2_2+M.2_3". I didnt even install a M2 in M.2_2 and M.2_3. I only have an M.2 in M.2_1 and in the Dimm2.Modul.

    What i tried so far:
    • Doing a CMOS reset,
    • Installing a fresh new BIOS (0504),
    • Reinstalling Chipsetdrivers (,
    • DDU uninstalling the Nvidia drivers and reinstalling the GPU driver again.

      New Windows 11 installation (Win 11 V. 22000.493)

    I tried out an other Graphics card (3070) - same error, only PCI8x avaliable

    Then i changed the Mainboard to my other x570 - there everything works fine with 16x4.0

    My Specs: Ryzen 5900x, 64GB DDR4 Corsair Vengeance 3600 CL 18 (D.O.C.P) enabled), RTX 3080

    No OC on Ram or CPU

    Did i miss something or do you think the MB has to RMAj - whats confusing for me is that first few day everything worked fine, since the Bootup Message i have that problem.

    Best regards!
    Last edited by pz123456; 02-12-2022 at 08:40 AM.

  2. #2
    ROG Member Array marti77 PC Specs
    marti77 PC Specs
    MotherboardRog Crosshair VIII Extreme
    ProcessorRyzen 9 5950x
    Memory (part number)F4-3600C14Q-32GTZNA
    Graphics Card #1EVGA RTX SC Ultra 2080Ti with EK Block
    Sound CardSupreme FX/nvidia HDMI out
    MonitorASUS PG329Q
    Storage #1Samsung 980 Pro 1Tb
    Storage #2Samsung 870 Evo 4TB/ 970 evo plus 2TB
    CPU CoolerTechN Block
    CaseCorsair 900D
    Power SupplySeasonic Prime Ultra 1000 Titanium
    Keyboard Logitech G915
    Mouse Logitech G903
    Headset Sony WH-1000XM3
    Mouse Pad Roccat Sense
    Headset/Speakers Chorus compact 662
    OS Win 10 Pro
    Network RouterNetgear Nighthawk RAX200
    Accessory #1 Denon AVR-X2600H
    Accessory #2 Logitech G27
    Accessory #3 Microsoft sidewinder Pro
    marti77's Avatar
    Join Date
    Jan 2015

    You cant use cpu pcie config mode: "PCIEx16_1+M.2_2+M.2_3 its revert to 8x mode so m2_2 and m2_3 slot cant be used in this motherboard if you want to have 16x mode.
    I know its a stupid flaw in this board and you can only use m2_1 slot and the dim2 module.
    For a high end board its a bad decision from asus.

  3. #3
    New ROGer Array
    Join Date
    Sep 2021

    thanks for your reply @marti77

    whats curious about that x8 speed is that it first run fine with 16x4.0 - then it reduced the speed on to x8 "on its own"-i changed no hardware, no bios settings at that point.

    PC bootet up and i got that message.

    I contacted Asus inbetween - they think the mainboard might be broken and i should send it in to RMA.

    Problem is, i bought it private. The seller refuses to refund anything.

    Im still not sure if its a hardware issue - do you have the same board? can you manage your PCIE_1 to run at 16x speed?

    I had no M.2 in M2_2 or M2_3, only in M2_1 and the Dimm-Module

    Best regards
    Last edited by pz123456; 02-21-2022 at 08:38 AM.

  4. #4
    New ROGer Array
    Join Date
    Sep 2021

    Solved - PCI-E 8x instead of 8x

    Hello guys,

    i just wanted to let you know i think i found the solution to my problem.

    Yesterday i tried a different CPU and a different RAM-Kit.

    After changing my 3600 Mhz 64 GB kit to an G.Skill 3000 Mhz CL 15 my PCI-E Speed was again 16x - same Bios settings, everything else the same. All i switched was the RAM.

    It doesnt make any sense to my, cause there was no OC on my Ram before and it runs regularly with the 570-F Gaming.

    Just wanted to let you know. In case i can help someone before you return your Board.

    I would never thougt - its the Ram, i thougt its the Board or CPU.


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