Why cant I enabled GSYNC and Adaptive Vsync (Half Refresh)????

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by CPC_RedDawn, Aug 23, 2017.

  1. CPC_RedDawn

    CPC_RedDawn Ancient Guru

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    Just wanted to test this out, I have a 144Hz monitor and wanted to test out the Adaptive Vsync (Half) so 72Hz settings.

    However, I don't want tearing so I wanted GSYNC enabled as well but when enabling GSYNC I can only select under Vsync option On/Off/Fast/Use App 3D setting...

    Why is this? GSYNC should work between 30fps - Monitors Max Refresh (144Hz for me).

    Sure I could just use a frame limiter and lock to 72fps but why is this not allowed within the drivers?

    Using 385.28 WHQL
     
  2. dr_rus

    dr_rus Ancient Guru

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    Well, the obvious answer is because there is no vsync inside the gsync range when gsync is active.

    The question of why NV doesn't expose existing features like fps limiter in their own CPL is an interesting one, and I've yet to hear anything from NV on this.
     
  3. CPC_RedDawn

    CPC_RedDawn Ancient Guru

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    Isn't GSYNC just altering the monitors refresh rate to match that of the displayed fps in game as long as it's within range. So technically there is 114 vsync ranges within the 30fps - 144fps GSYNC range? GSYNC just enables vsync but in an adaptive way within its range... See what I mean?

    EDIT:

    I have enabled what I wanted to do within RTSS anyway, and 72fps locked using its frame limiter. It's actually quite nice, gsync means no tearing, the game won't go above the gsync range so vsync wont enable or tearing wont occur if vsync is turned off. Its a win win to be honest. Not sure why more people don't do this. Sure you are not getting 144fps or you could just cap to 142fps but getting every game to that frame rate means sacrificing a lot of settings depending on the game or the power of your hardware.
     
  4. dr_rus

    dr_rus Ancient Guru

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    It does alter monitor refresh rate so that it is the same as the fps a game is outputting but this isn't what vsync does and thus this isn't vsync.
    I do wonder what makes vsync engage on highest display refresh rate though, seems like a design flaw.
     

  5. fantaskarsef

    fantaskarsef Ancient Guru

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    Sorry that I can't help with the issue, but that whole thing on how to properly use Gsync is still mysterious (haven't been using Vsync since I got my Gsync screen, although I'm still doing it wrong without noticing tearing).
     
  6. Agent-A01

    Agent-A01 Ancient Guru

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    I recommend you to read Gsync 101 article to get you up to speed on how G. Sync works.

    Enabling adaptive half refresh rate would be useless.

    Max refresh rate does not enable vsync as drivers have Vsync is disabled by default.

    Again, design flaw?
    Read Gsync 101 article.
     
  7. dr_rus

    dr_rus Ancient Guru

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    So what happens at top refresh rate with gsync by default? It just goes out of range and starts tearing?

    (Sometimes I wish I haven't bought my current U3014 monitor as it seems that I'll have to wait for about five more years until there will be an all around solid replacement with Gsync and stuff.)
     
  8. gdallsk

    gdallsk Active Member

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    That's exactly what happens, thats why people tend to lock the framerate 3-4 fps below the max refresh rate, as that is where the G-Sync cut off point tends to be.
     
  9. dr_rus

    dr_rus Ancient Guru

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    Hence the design flaw comment as it's not clear to me why you can't lock the framerate at the top Gsync range number.
     
  10. nevcairiel

    nevcairiel Member Guru

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    But why does it have to get to 142 fps in the first place? The whole point of GSYNC is that you don't have to run at max all the time. You could cap at 142 to avoid the VSYNC latency and if the game still runs at 72 fps because it won't go faster, then thats what it'll do, and GSYNC will handle it just fine.
    What is the advantage in capping it lower in the first place?
     
    Last edited: Aug 23, 2017

  11. Agent-A01

    Agent-A01 Ancient Guru

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    Because frame limiters aren't perfectly accurate so setting a limit to the max refresh rate will get an on off vsync behavior, which is not good.

    And it's not possible to limit FPS internally(monitor) either.
    Nor is that functionality possible in the foreseeable future yet.
     
  12. dr_rus

    dr_rus Ancient Guru

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    RTSS limiter is absolutely accurate in my experience. NV's V2 limiter is pretty good as well.
     
  13. Agent-A01

    Agent-A01 Ancient Guru

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    That theory is debunked because if you set a FPS limit to the decimal of said monitor( example 144.003 hz) you will get vsync on.

    It will still hit the ceiling or go above it.
     
  14. RealNC

    RealNC Maha Guru

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    Consistency. Some people (including me) find it annoying if the FPS changes too much. If a game runs at 80-100FPS for example most of the time, but sometimes it goes up to 140, I just cap to 90 so it always (or almost always) has the same smoothness of motion to it and the same motion blur.

    This is subjective, of course. If that doesn't bother you, then you don't need to do that.

    There is another, non-subjective reason though: capping the framerate to a value low enough where the game always hits the cap will reduce input lag by 1 or 2 frames. This has nothing to do with g-sync though. This also happens without g-sync. If the game runs uncapped, it has higher input lag compared to capping it. For example if you play Overwatch, but your FPS is usually 130 for example, then you get lower input lag if you cap it to 130 instead of 142.
     
    Last edited: Aug 24, 2017
  15. Shadowdane

    Shadowdane Maha Guru

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    I just use RTSS to cap my FPS to the highest stable fps I can manage! I prefer fps that doesn't fluctuate so it just feels smoother compared to fps that bounces around between say 80-110fps.
     

  16. Mda400

    Mda400 Master Guru

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    Right, because the variance in frametime may throw off your muscle memory of what for example, a consistent 60fps/16.67ms feels like versus a variation of going from 144fps/7.8ms down to 60fps/16.67ms when there's a lot of action onscreen.

    You say non-subjective, but yet isn't throttling the renderer going to create more delay rather than let it run uncapped/unthrottled? There's also the perception of delay when running the framerate over the refresh rate as frames are being shown out of order on the display.
     
    Last edited: Sep 11, 2017
  17. yasamoka

    yasamoka Ancient Guru

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    That's not true. Hitting the framerate cap actually increases latency, not the other way round. One of two scenarios:
    1) Internal framerate limiter: higher frametimes lead to marginally higher latency
    2) External framerate limiter: RTSS, the best, introduces a delay of 1 frame due to limiting framerate later on in the chain relative to an internal framerate limiter

    Leaving the framerate uncapped is always guaranteed to be the lowest latency scenario.
     
  18. jorimt

    jorimt Member

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    It is true, actually.

    As long as it is the framerate's limiting factor, an in-game limiter actually reduces latency over uncapped at the same framerate (at least if we're talking within the refresh rate), regardless of G-SYNC.

    RTSS introduces more latency when compared to the in-game limiter, as it sets a frametime target (in-game sets a framerate target, and thus can still utilize lower frametimes to deliver frames faster), but even it reduces latency of uncapped at the same framerate.

    It has to do with how the game's engine calculates the render time of the frame; with uncapped, an ever fluctuating framerate means the engine must calculate a different frametime (sometimes much higher, sometime much lower) for each frame before it begins rendering; the pre-rendered frame queue/settings applies in this scenario.

    However, with a limiter, as long as the framerate is being limited by it, the engine know exactly when the next frame is needed/what frametime can be sustained, and delay is decreased; the pre-rendered frame queue/settings no longer applies/matters is this scenario.

    I didn't include it in my G-SYNC 101 series because it was beyond both the scope of the subject and my testing parameters (not directly related to syncing methods).

    There are exceptions (V-SYNC OFF and uncapped with framerates far higher than the refresh rate, etc.), but that's for another conversation.
     
    Last edited: Sep 14, 2017 at 3:15 AM
  19. RealNC

    RealNC Maha Guru

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    Jorim already explained a few things, but think of it this way: uncapped framerates mean multiple buffers filled with frames, which introduce input lag. Capped frame rates mean the frame buffers are now empty, meaning no input lag.

    Also, RTSS does not add input lag. It is neutral. In-game limiters can reduce input lag, RTSS is just neutral; it neither adds nor reduces input lag on its own. Input lag is still reduced when capping with RTSS, but not because of RTSS (as I said; it's neutral) but because of the frame cap itself.

    So,

    Uncapped: Baseline.
    In-game capped: Much less input lag than baseline.
    RTSS capped: Less input lag than baseline.
     
    Last edited: Sep 16, 2017 at 10:19 PM

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