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LFC out of sync (Freesync issue)

Discussion in 'Videocards - AMD Radeon Drivers Section' started by Synoxia, Jun 21, 2019.

  1. Synoxia

    Synoxia Member Guru

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    Anyone is noticing out of sync LFC issue? Very easy to spot because it causes tearing or small hitches.
    Otherwhise use monitor OSD to see refresh rates.
    Example 45 fps = LFC 90hz > random jumps to 100 and 120 hz
    Issue doesn't seem to happen in normal freesync range (example 45fps = 45hz)

    GPU is vega 64, windows 1903, drivers 19.6.2, CPU 2700X with latest chipset.
    Monitor is XG2401 v1

    Game is batman arkham knight but i also tested this on Witcher 3
     
    Last edited: Jun 21, 2019
  2. Fox2232

    Fox2232 Ancient Guru

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    monitors do not display fps as an average. They usually display per frame value... 1 divided by frametime.
    My 240Hz screen's OS show high variation even within FS range. (Not that I have ever seen tearing, but I am not running under minimum fps.)
     
  3. Synoxia

    Synoxia Member Guru

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    I can clearly see some hitches when this happens... a small variation seems acceptable (60fps = 59.8-60.2hz but not jumps to 62hz for example)
     
  4. Fox2232

    Fox2232 Ancient Guru

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    Frametimes have much higher variance. And therefore reported fps should have same.
    Please understand that it is per frame variance, not average per second.
     

  5. Krteq

    Krteq Master Guru

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    Synoxia, FreeSync range for your monitor is 45 - 144 Hz, right?

    So, if you are in that range, LFC isn't active. LFC is working only below min. range, you know - Low Framerate Compensation. Next thing, monitor OSD can't render current refresh rate in real-time.

    When you are in FreeSync range, there is no matter how many FPS you have. If FreeSync is working fine, you shouldn't get any tearing or "hitches".

    Can you please try to explain what exactly is happening on your monitor?
     
  6. Synoxia

    Synoxia Member Guru

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    My Monitor range is 48-144. When i fall below that, example 45fps, i should be getting 90hz refresh rate, which doesn't happen. It goes around 89-90 hz for a while then 100-120hz.
    I modified Freesync range to 40-144hz. This is what happens at 43fps

    Without this workaround i would be getting something like 86HZ-100hz instead of something around 86hz.

    Example of this behaviour which happened a while ago and i thought it was fixed (seems to be fixed >60hz freesync range but either LFC range or custom freesync range is broken with the latter being less broken than stock LFC)

     
  7. Jayson

    Jayson Member

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    I have a similar LFC issue with my MG278Q (40-144Hz). Ever since I updated past 18.5.1, entering or exiting the LFC range causes major stutter until it smooths out. If I'm hinging on 40fps, then it will stutter pretty much constantly until it's consistently under 40fps or consistently over 40fps. If I install drivers 18.5.1 again, it's a seemless transition between LFC and native FreeSync. I've reported this issue many time to the driver team and they still haven't fixed it. Why was it okay in 18.5.1 and lower? What changed since then? I don't know, but it's really annoying. Since then, I just have to adjust settings to let me stay above 40fps or I have to cap my frame rate to 30 or 35 to avoid stutter. It sucks.
     
  8. OnnA

    OnnA Ancient Guru

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  9. Synoxia

    Synoxia Member Guru

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  10. Fox2232

    Fox2232 Ancient Guru

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    There is no logic in reducing lower freesync range since there is LFC. And lower range is mere 1/3rd of higher limit. Therefore frame display doubling is always able to work.
     

  11. nikobellic

    nikobellic New Member

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    I have LG monitor with a range of 40-75Hz, I tried to extend the range with CRU so that LFC works. I tried 37-75Hz, LFC works but I see blank screen sometimes, then tried 37-74Hz (creating 74Hz with "LCD Reduced"), it was working really good till 18.6.1, then something changed in the driver and there is huge stuttering when FPS droped around 32-37, so I kept using 18.6.1 until I found this post where a user mentioned that reducing the blanking helped him achieve a near perfect LFC, I used his settings and voila, no stuttering even in newest driver https://www.monitortests.com/forum/Thread-Custom-Resolution-Utility-CRU?pid=8572#pid8572
     
    Jayson likes this.
  12. Synoxia

    Synoxia Member Guru

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    I dont understand what he did... do i have to reduce [​IMG] this to something like 60 and LFC won't be broken anymore?



    https://forums.guru3d.com/threads/freesync-is-broken.424805/page-2 i just realized i complained about this a while ago, check that user freesync behaviour, i am now tilted to maximum level and gonna buy a new monitor asap unless i figure out what's going on
     
    Last edited: Jun 26, 2019
  13. Fox2232

    Fox2232 Ancient Guru

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    @Synoxia : I used to have Black/blank screen issue at some times. ON screen with rated FS range of 48 to 240Hz. I did many experiments with different settings in CRU.
    Some managed to reduce rate at which this issue occurred, bet never really removed it.

    Then I simply increased lower FS limit from 48 to 50Hz. And issue solved.

    As for reduced porches/blanking, it is kind of synchronization overhead. Smaller the value, smaller data rate required towards monitor, but higher chance of issues if screen can't detect where image starts/ends.
    If your screen dislikes Pixel Clock above certain frequency, then reducing this may help.
     
  14. Synoxia

    Synoxia Member Guru

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    @Fox2232 Here the problem is that my monitor/gpu can't follow fps/frametimes correctly with refresh rate.
    check this guy behavior at 30fps this guy has a max of 0.4 refresh fluctuation in worst cases.
    i have weird fluctuations, even AMD support recognized this and suggested me a clean driver reinstall (which i already did more than 10 times but whatever)
    In my best scenario, even with RTSS capped game at 50fps i get from 49 to 51hz.... now i don't know if nvidia pendulum caps frametimes better than RTSS but clearly something is wrong!
     
  15. Fox2232

    Fox2232 Ancient Guru

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    @Synoxia : What about HPET? All newer builds of W10 should have it enabled... same goes for BIOS.
     

  16. Synoxia

    Synoxia Member Guru

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    @Fox2232 X470 asus ch7 has no option for HPET, idk if it's enabled or not but i've disabled it with useplatformclock /false. Do you think enabling it makes a difference?
     
  17. Fox2232

    Fox2232 Ancient Guru

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    Yes, it should be enabled for any and all purposes on W10.
    Doesn't ASUS have some windows based software for BIOS control where given option may be available? It is weird to have BIOS without it.
    (I think that if it is not shown, it should be enabled by default.)
     
  18. Synoxia

    Synoxia Member Guru

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    You mean FORCE enable it? bcdedit useplatformclock /true? I had force disabled it via device manager and useplatform /false.
    Now i'm trying stock windows 10 settings (stock device manager, /deletevalue, means HPET mostly off but ON if needed) and dynamictick disabled


    this test shows best results are with w10 stock settings

    And no, asus doesn't have an option for HPET for some reason, only way to control hpet is via windows.
     
  19. Fox2232

    Fox2232 Ancient Guru

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    Try it with Forced ON Too.
     
  20. Synoxia

    Synoxia Member Guru

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    Forced ON completely destroys Gsync pendulum demo. 30fps with RTSS/in app cap? > 66hz/133hz. Wonderful.
    Games are unaffected (or more appropriately, always broken in the same manner)
    https://forums.guru3d.com/threads/freesync-is-broken.424805/page-2 Which thread is more appropriate to continue with this issue? That was a bit of necropost but its my same thread, seems like freesync is just broken not only LFC
     

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