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  1. #1
    ROG Enthusiast Array
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    MCLK vs FCLK vs UCLK

    My rig:

    - Ryzen 9 3900X 3rd Generation GHz (4.6 GHz Max Boost) Socket AM4 Unlocked Desktop Processor

    - ASUS - ROG Crosshair VIII Hero (Socket AM4) USB-C Gen2 AMD Motherboard with LED Lighting

    - CORSAIR - VENGEANCE RGB PRO 32GB (2x16GB) DDR4 3600 (PC4-28800) C18 Desktop Memory

    ZenTimings: MCLK 1067.00
    FLCK 1200.00
    UCLK 1067.00

    I've read in several places that FLCk and ULCK should have a 1:1 ratio. Should I make changes to FLCK? If yes, I don't see where to change in BIOS.

    Help please...

  2. #2
    Administrator Array Silent Scone@ROG's Avatar
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    The FCLK(Fabric Clock) and memory should be run in a 1:1 ratio in order to obtain the lowest latency, yes. On majority of UEFI builds FCLK should sync to the memory speed, however, you can sync it manually by changing the fabric clock in the UEFI (FCLK Frequency)

    There is no need to change UCLK as this is the memory controller, and thus synced to the speed of the fabric.


    You can check in CPUZ whether or not the FClock is scaling correctly.


    Click image for larger version. 

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    Last edited by Silent Scone@ROG; 07-14-2021 at 06:57 AM.

  3. #3
    ROG Enthusiast Array
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    Thanks!!!

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