How does AB apply an overclock?

Discussion in 'MSI AfterBurner Overclock Application Discussion' started by derpyQ, Jan 15, 2017.

  1. derpyQ

    derpyQ Active Member

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    May seem like an abstract question, but I was wondering since AB's overclocks and fan profiles and such continue to work after closing the program, what the mechanism of this is?

    In fact, how do stock clocks and fan profiles on GPUs work? Is there a part of the GPU's RAM that's dedicated to storing that information? And then Afterburner can overwrite that?
     
  2. Maddness

    Maddness Master Guru

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    It's all stored in the cards bios.
     
  3. derpyQ

    derpyQ Active Member

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    so AB is modifying the BIOS every time you hit apply? seems unlikely..
     
  4. JonasBeckman

    JonasBeckman Ancient Guru

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    Pretty sure for AMD cards at least this is set in the registry, also why 4.3.0 has a new option to wipe said data on reboot (Which I guess is then re-set when AB is next started.) as to avoid problems with a unstable OC getting applied during boot and possibly crashing the GPU or system.

    Not entirely sure as to where in the registry it would store that information though, probably one could perhaps trace where Wattman saves any changes unless it uses some separate method?
     

  5. Maddness

    Maddness Master Guru

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    My apologies. I thought you were talking about AIB's clocks. Not MSI Afterburner. I misread that.
     
  6. derpyQ

    derpyQ Active Member

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    Do you happen to know if it's the same for Nvidia?

    No sorry, I also did add that as an afterthought. But I am def interested in how AB alters these values.
     
  7. JonasBeckman

    JonasBeckman Ancient Guru

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    I would assume it works similar for Nvidia although there's a difference in API which I think AMD's is called something like ADL and for Nvidia it's NvAPI.

    Still have to store the information somewhere and the registry is probably the best option although it's been some years since I used a Nvidia GPU myself though thinking about it since the option for wiping overclock settings in Afterburner is specifically for AMD compatibility chances are there's some other factor with Nvidia GPU's or at least it avoids deadlocking the system during boot by reverting to safe/default values on failure?
     
  8. Unwinder

    Unwinder Moderator Staff Member

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    Wrong.
    Simply think why absolutely any overclocking tool contain the option called "Apply overclocking at Windows startup". The reason is simple: the settings are not written by overclocking tools in "GPU RAM", BIOS, registry or anywhere else and have to be re-applied after each OS startup.
     
  9. EdKiefer

    EdKiefer Maha Guru

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    Memory, thats why reboot or even driver crash can change clocks.

    registry would be bad, bad OC , looping crashes.
     
  10. JonasBeckman

    JonasBeckman Ancient Guru

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    Interesting, wouldn't have though about storing it in memory though thinking about it that does clear up why the compatibility option for AMD GPU's exist if it's that problematic with it being retained via registry. :)

    Which I guess it would be, Wattman is supposed to revert to safe or default values on a crash but if the registry information is loaded before that can be done that would lead to a loop of crashes.
     
    Last edited: Jan 16, 2017

  11. derpyQ

    derpyQ Active Member

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    Thanks. Is that the same for both the "default"/BIOS profile and something applied by a third-party prog?

    And further, assuming this fan/voltage/clock information from the vBIOS resides in system RAM, is there any difference between that and a profile being set via a third-party program? In other words, if you were to apply a profile in AB, would the information stored in RAM be any different than if the vBIOS had been modified with the same profile you'd applied in AB?
     
  12. EdKiefer

    EdKiefer Maha Guru

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    Unwinder , would be much better in answering this as I have no experience with AMD side.
    But if I understand your question a bios edited to same values as a base OEM vid plus 3rd party OC. The bios method is better as its more fine grained as to boost and voltage tables.
    So the software OC is adding a offset to whatever it can (GPU core, memory, voltages).
    Many times you have more flexible settings coverage in bios editing.
    Downside of bios is if you go for peak OC, and a new driver/game might make that unstable, so it's easy to change if this happened when your using software method

    I personally run edited bios and AB as they both have there strength's as mentioned above.
     

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