Do control panel post process effects (Sharpening / FXAA / etc) add input lag?

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by BlindBison, Sep 21, 2021.

  1. BlindBison

    BlindBison Master Guru

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    I know that each effect is very inexpensive and adds some minor amount to frametime, but I expect that would be reflected in the ultimate framerate that's reported no?

    So, for example if you get 65 fps without any of those effects then get 64 or 63 with both the sharpen and fxaa ON lets say for sake of theory, of course there's a slightly higher amount of input lag due to the reduced framerate caused by enabling the effects.

    My question is, if you're playing a game capped to a target framerate like 60 FPS then add on the control panel CAS Sharpen + FXAA, does it add any additional input lag so long as you've got the headroom to maintain 60 FPS? Or does it always add a small amount of delay regardless of framerate/GPU overhead?

    Thanks!
     
  2. dr_rus

    dr_rus Ancient Guru

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    No.

    I have no idea why people think that PP adds input lag besides that which is a result of a lower framerate. If you're running a game locked to some framerate then increasing the GPU load is more likely to lower input lag, not increase it.
     
  3. Dragam1337

    Dragam1337 Ancient Guru

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    Really... -_-

    Increasing gpu load will NEVER lower input latency, unless it's because you are simply running the game at higher fps...
     
  4. hemla

    hemla Master Guru

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    If increasing GPU load would also decrease CPU load and you would be in CPU bottleneck scenario...
     

  5. BlindBison

    BlindBison Master Guru

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    Thanks guys!
     
  6. dr_rus

    dr_rus Ancient Guru

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    It will if the result of such increase would lead to less frames being stuck in the CPU side enqueue.
     
  7. Dragam1337

    Dragam1337 Ancient Guru

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    That's not how it works...
     
  8. dr_rus

    dr_rus Ancient Guru

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    It's exactly how it works when you're limiting the framerate.
     
  9. hearnia_2K

    hearnia_2K Active Member

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    If using low latency or ultra lw latency, or using gsync and not hitting your monitors top refresh rate then ANY increase in GPU load also increases the lag betwene the input and you seeing it on the display.
     
  10. Astyanax

    Astyanax Ancient Guru

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    false
     

  11. CrazyGenio

    CrazyGenio Master Guru

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    I came to check the forums after a long time just to see the forums are still full of people with no idea of what they are talking.

    - high GPU load with low CPU load is not a CPU bottleneck.

    - High GPU load does not increase input lag. most people think this is the cause but it is not, the issue is that some gpu even at full load struggle to get stable and constant framerate, so the cause is the unstable and low fps, not that the gpu is at full load.

    - Not hitting your monitor max refresh rate don't cause input lag, you are just not getting the input lag expected when the monitor is actually used in its full potential, hence the feeling of sluggishness and high input lag, so again the cause it's the unstable and low fps.

    Yeah but probably I'm wrong, after all, I'm in the forums where people can't see the difference between 1080p 1440p and 4K.
     
    Cave Waverider likes this.
  12. hemla

    hemla Master Guru

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    Yes, you are wrong. You don't understand this sentence: "If increasing GPU load would also decrease CPU load and you would be in CPU bottleneck scenario..." while pretending to be smartass.
     
  13. CrazyGenio

    CrazyGenio Master Guru

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    whatever makes you happy, not gonna argue here, last time i argued here i ended knowing that a 20 inch 1080p monitor is better than a 27 inch 1440p monitor.

    I don't know what else i'm going to "learn" here in these super big brain guru forums until people consider me right.
     
  14. BlindBison

    BlindBison Master Guru

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    Not sure how the pixel density works out for those panels, but unless you take Apple's approach of using bizarre resolutions that maintain a specific pixel density across sizes couldn't a smaller 1080p screen be more pixel dense in theory than a larger 1440p one? There's more to judging a display than just pixel density, but my understanding was that's why handhelds can look so sharp running games on their tiny lower rez panels. The Vita was 540p, but games still looked pretty sharp due to the pixel density for example.

    If I'm misunderstanding something feel free to correct me, I'm not as knowledgeable on this stuff as some others on the forum board. Personally i'd also rather have the 27 inch 1440p monitor in your scenario.
     
  15. Dagda

    Dagda Master Guru

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    no, post process will not give you any latency.
     

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