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The truth about PRE-RENDERING 0?

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by Tastic, Jul 16, 2012.

  1. AsiJu

    AsiJu Ancient Guru

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    Question: if I use a frame rate limiter with vsync and cap to refresh rate, that should afaik keep back buffers empty, does amount of pre-rendered frames make a difference to input lag anymore?

    I usually set cap + vsync + 1 frame pre-render but is the last step actually redundant?
     
  2. Xul Aethyr

    Xul Aethyr Member

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    Yes it does
     
  3. RealNC

    RealNC Ancient Guru

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    You need to cap slightly below the refresh rate. And the refresh rate, in the majority of cases, is not what you think it is. See:

    https://forums.guru3d.com/threads/the-truth-about-pre-rendering-0.365860/page-12#post-5380262

    The max pre-rendered frames (MPRF) setting has an effect when the frame cap is not reached. So it's not redundant. Basically, when your FPS does not fall below the cap value, input lag is AS IF you were using an MPRF setting of 0 (which isn't possible, but since buffers stay empty, it's AS IF it was set to 0.) When your FPS falls below the cap value, then MPRF comes into effect.

    However, you can run into issues where frame rate gets halved if you set MPRF to 1 and the frame rate falls below the cap. This can result in some really bad stutter, because frame interval times will fluctuate a lot when this happens. This depends on each game. If you see stutter with MPRF 1, then try setting it to 2.
     
    Last edited: Mar 20, 2018
  4. AsiJu

    AsiJu Ancient Guru

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    Thanks, so I'll keep setting it as before. Or capping to slightly below refresh rate.

    I often use ingame limiters though if they seem to work all right so use even numbers. RTSS when ingame limiter isn't optimal or there isn't one.
    Plus using CRU to get even 75.000 Hz gives pretty good results when capping to 75.
     

  5. RealNC

    RealNC Ancient Guru

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    In-game limiters cannot keep sub-millisecond precision. RTSS can.

    You also need to measure your real refresh rate for this to work. If you cap to even frame rates, you're only getting partial input lag reduction. By doing it correctly, your input lag is going to be between 0 and 1 frame.

    Again, if you read the post I linked to, things should become clear.
     
  6. AsiJu

    AsiJu Ancient Guru

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    Yes but using CRU to create an even 75 Hz means actual refresh rate is even 75.000 Hz or am I mistaken?

    Ofc I should then cap to slightly below 75 fps (74.993) for best results but I've found capping to 75 when refresh rate is 75 gives satisfactory results.

    The monitor default 60 Hz mode is actually 59.94 Hz.
     
  7. RealNC

    RealNC Ancient Guru

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    If you're using CRU then the way to go is to use 75.008Hz (or somewhere near that, like 75.010 or 75.012; whatever CRU rounds it to.)

    And of course test this on the refresh rate detector sites to make sure.

    (This was already mentioned in the linked-to post.)
     
  8. AsiJu

    AsiJu Ancient Guru

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    Right, thanks again.
     
  9. alexander1986

    alexander1986 Member Guru

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    this post is really good, a question here, what is the difference between capping refreshrate exactly 0.007 under with RTSS and vsync on + max prerender 1, compared to no vsync, but still prerender 1 and same RTSS cap ?

    also, is there any point at all enabling triple buffering and or vsync AFR smoothing in nvidia inspector if capping fps to 0.007 fps under true refreshrate ?


    thanks if anyone can answer this, cheers!
     
  10. RealNC

    RealNC Ancient Guru

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    There's no point in doing this without vsync. You can just cap your FPS to whatever you want when not using vsync.

    I'm not sure how frame capping affects triple buffering. TB increases input lag by 1 frame but reduces stutter if the frame rate falls below refresh rate. But whether or nor this is still true when using a frame limiter, I don't know. (Note that nvidia's TB setting only affects OpenGL and possibly Vulkan games.)

    I never used SLI so I don't know much about AFR.
     

  11. SeveN

    SeveN New Member

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    Hello, just wanted to make sure I got this set correctly. I have a 60hz monitor, oc'ed to 75 through control panel. Both test's gave me 75.002Hz, testing with 60Hz gave me 60,002Hz as well. So 75.002Hz - 0,01 = 74,992. I put 74992 in the limit line of the global file. I think it's working correctly, because I tested it with witcher 3, I have a particular save where it would always stutter few times when running foward, but this limit fixed it completely!
     
  12. RealNC

    RealNC Ancient Guru

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    Since you've OCed, there's no need to use a fractional limit. You can just OC to 75.010Hz (or near that, like 75.011, 75.012, whatever CRU rounds to.) Then cap to 75FPS.
     
  13. SeveN

    SeveN New Member

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    I didn't use CRU tho. For OC I used nvidia control panel by creating custom resolution, but it doesn't allow numbers after "." or "," only full numbers so I set it to 75, but after testing it with those 2 sites, the actual number is 75.002hz, so by setting framelimit to 74,992, I've done everything correctly?
     
  14. RealNC

    RealNC Ancient Guru

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    Yes.
     
  15. SeveN

    SeveN New Member

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    This is strange, I was doing more test's and turns out it was the vsync alone that got rid of some stutter. I disabled the vsync and framers aren't capped by rtts. I did what you said, I set :

    [Framerate]
    Limit=74992

    and in rtts window I can see framerate limit 74992, but this value doesn't seem to work. I tried to add "." so I typed Limit=74.992 in global file and saved. The cap seems to be working, frames are locked at 74, just as rtts window shows, but idk if the framers aren't just locked at 74, and maybe rtts is ignoring numbers after dot. You said

    " Too low and the trick doesn't work anymore, too high and you get repeated frames that result in "hiccups".

    So i need to get this specific value to lock, but idk how to do it, rtts doesn't seem to allow it.
     

  16. RealNC

    RealNC Ancient Guru

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    It looks like you didn't set LimitDenominator to 1000? Read the post again:

    https://forums.guru3d.com/threads/the-truth-about-pre-rendering-0.365860/page-12#post-5380262
     
  17. SeveN

    SeveN New Member

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    Yes because there is no "LimitDenominator" in my global file, here's how it looks like https://pastebin.com/TTWpHbTR


    edit : nvm so you need to add this line manually? Because I just did and it seems to work. You should have mentioned that. Thought maybe this line existed in some older version of rtts back then when you posted that or something, and they removed it later on.
     
    Last edited: May 6, 2018
  18. SeveN

    SeveN New Member

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    btw, now after googling that "LimitDenominator " thing, I came across few guides such as this https://www.blurbusters.com/howto-low-lag-vsync-on/ it's the exact same method as yours, but it says we could try testing it with fast sync instead of default vsync to " to allow tighter frame rate capping for the purposes of avoiding stutters." What's your opinion on this? You only mentioned standard vsync in your post.
     
  19. JonasBeckman

    JonasBeckman Ancient Guru

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    ProfileTemplates/Global is where you can find the full list of settings which can then be copied over into Profile\Global if you want to change them. Goes for the Config file too as I recall.
    And then there should be a setting for IntegerFramerate which if disabled should show the values as float numbers instead of integer ones so say 59.9 instead of 59 though I could be remembering it wrong how many digits it displayed.
     
  20. Astyanax

    Astyanax Ancient Guru

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    Or you can just set RTSS to show the pre-defined profiles.....
     

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