Hysteresis in custom fan curve not working

Discussion in 'MSI AfterBurner Application Development Forum' started by Arezian, Nov 26, 2017.

  1. Arezian

    Arezian New Member

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    Hi guys,

    I recently had to reinstall MSI Afterburner and had to completely redo my setup from scratch. I did the custom fan curve just like I had it before and as you can see in the image below. Also the settings for hysteresis are identical. It worked without problem before reinstalling, but now the hysteresis does'nt work. When the GPU tempreature goes above 45°C the fan rotates at 30% of max RPM. According to my settings, the fan should go to 0% speed when the temperature reaches 40°C (<45°C - 4°C from hysteresis). Now the fan stops spinning directly at 44°C so just when the actual temperature falls below the trigger temp. This causes my fan to start and stop constantly in small time intervals. Is there any setting I missed?

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    Last edited: Nov 26, 2017
  2. Spirit1408

    Spirit1408 New Member

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    Greetings.
    I have the same trouble. Have you find a solution yet?
     
  3. boogieman

    boogieman Ancient Guru

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    To me it means your fan curve isn't tweaked enough. It's right on the hairy edge from needing to spin and then turn off. I keep my fan on at 50% until GPU reaches 32c then shut it off because I know my GPU at no load does not exceed 30c. Everyone's situation is different based on case cooling and ambient temp.
     
  4. EdKiefer

    EdKiefer Ancient Guru

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    That staircase of points are badly positioned IMO.

    What I would do is first do it with straight lines, curving up to the right. when you have it good, double click on the graph to set those points to staircase mode.

    Note you can have up to 8 points.
     

  5. sfenson

    sfenson New Member

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    were you able to resolve this? same issue after upgrade
     
  6. Unwinder

    Unwinder Moderator Staff Member

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    Search to understand what is hysteresis and how it is supposed to work.
     
  7. sfenson

    sfenson New Member

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    i've searched and read every post on this subforum that contains word "hysteresis" and there was nothing that would point me to a solution
    in the scenario where hysteresis is needed below 0 pwm duty cycle point in the custom fan curve.
    i understand the feature, it was already working for me in that scenario a couple versions back, recently i upgraded AB and now it doesnt work as before.
    today i also did a clean install and reconfigured all the settings (which didn't help).

    can you at least allow for the remote possibility that it is not working in a very specific scenario due to a bug you have not encountered?
    especially when it was working before?
    i have "force fan speed update on each period" enabled, and no other software installed that would attempt to change gpu fan speed.
    also afterburner is clearly able to turn off the fan at the desired point in the custom fan curve, if i change the 0 pwm point to a different temperature AB follows but without hysteresis.
    this was tested with 4.6.1 and 4.6.2b1 with stair stepped and linear fan curves.

    i already was thinking about a workaround with autoswitching profiles between 2d and 3d but custom fan curve is not saved as part of the profile.
     
  8. Unwinder

    Unwinder Moderator Staff Member

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    I've said that it is lack of understanding of hysteresis and fan stop control functionality. No need to involve me into "it is bug you've not encountered" discussion. It is understanding bug and I have nothing to add to it. The link I provided above discusses hysteresis functionality in details.
     
  9. Unwinder

    Unwinder Moderator Staff Member

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    I had to pay attention to that statement, my bad. By forcing fan speed update on each period you're effectively killing any effect of hysteresis. Disable it.
     
  10. sfenson

    sfenson New Member

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    thanks for the tip, now it is stopping the fan at lower temperature.
    with the simplest 0db stepped fan curve with 1 step it is behaving always in the same correct manner.
    BUT if i add more fan curve steps it is inconsistent:

    [​IMG]

    hysteresis 5C, fan curve with 0% pwm duty cycle point at 45C and afterburner is stopping the fan at different temperatures, everywhere between 40-44C.

    can you modify the code to add better handling for 0rpm mode hysteresis so that in the example above
    it would always stop at 40C?

    you would just need to:
    1. find in your temp-duty cycle lookup table the first index (temperature) for which the duty cycle is greater than 0
    2. substract hysteresis from it
    3. in the code that changes the fan speed if the new found pwm duty cycle is 0 only update when temperature is less than or equal to temperature calculated in step 2.

    if you dont have the time i am willing to do this myself if you send me the relevant piece of code.
     

  11. Unwinder

    Unwinder Moderator Staff Member

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    It is NOT inconsistent, hysteresis is NOT a simple delta like you think. And no, implementation cannot be changed the way you want because it is not working this way. Furthermore I won't be able to provide you MSI AB code, it is a complete no go.
    Seriously, guys, I spend the second day FULLTIME answering questions from ASUS, EVGA and other brand card owners assuming that I'm here to explain anything on 24/7 schedule. I killed TWO days of my holidays on it instead of having a rest. I'm not even MSI support employee, and furthermore not ASUS support to make ASUS GPU owners happy. I'm sorry but I'm done with this question. Thread is closed.
     
  12. oldsantiago21

    oldsantiago21 New Member

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    Spent a few hours to find this out, thank you. Looking backwards, it is quite obvious, that it should disable hysteresis, but may be it would be reasonable to point this out in tooltip some way, in hints section or something

    edit: sorry for necroposting
     

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