Special K's new

Special K's new "Latent Sync" is vsync with as much, or even less, input latency than no vsync

For games where you have some GPU/CPU heardroom, use this feature to take the responsiveness to the next level


This new mode in Special K is very similar to "scanline sync" in RTSS, except it controls the render thread to reduce latency even more. Additionally, you can delay the game's render thread by a fraction of the frame rate to reduce input latency even more.

This feature is called "delay bias", you can see in the screenshot


For Hollow Knight I have it set at 75% input, 25% frame. This means that the rendering of the game is being delayed until the last 25% of the frame time, and therefore the polling of the input is also delayed.

Essentially, this means at 100hz, I get the the same input latency as if I was running the game at 400fps. You can also achieve latency like this by using something like Nvidia's fast sync, but with Special K, you have absolutely pefect frame pacing, and your GPU is resting instead of rendering a bunch of redundant frames.

Hollow Knight plays unbelievably snappy with this configuration. The little guy feels like he is electrically connected to the d-pad.

To enable latenct sync, you just click in the box for setting a frame rate limit, which brings up the submenu for Latent Sync

Latent sync will most useful to people without VRR or with it disabled. Say you're using BFI/strobing on a certain display and have to run a fixed refresh rate. Or if you're a based CRT user like me.

And Delay Bias is definitely a must for any game where you have enough GPU and CPU headroom to run well in excess of your max refresh rate, regardless of what display you're using.

Try it out and let me know what you think!


From The Chatty
  • reply
    March 22, 2022 11:25 AM

    Special K has a really cool new feature that is basically v-sync that can equal or even /[less]/ input latency than vsync off.

    Read more: Special K's new "Latent Sync" is vsync with as much, or even less, input latency than no vsync

    • reply
      March 22, 2022 11:32 AM

      Made a long chatty post and realized it would work better as a Cortex post. Hollow Knight was already playing really well but has made it even better.

      And I think I actually played a role in the additon of Delay Bias! GeDoSaTo has a frame delay feature, and many months back I hopped on the Special K discord to see if Kaldaien had anything like it hidden in Special K. A few months later it showed up!

      But yeah, another side note is that it doesn't work perfectly with everything. Like Mega Man 11 already has a built in frame cap. So for that game I used Special K's traditional vsync in combination with the frame cap and tweak called "low latency mode". This gives a very similar feel to the Latent Sync mentioned above, without the granularity you can see in that submenu.

      So yeah, long story short, Special K rules!

    • reply
      March 22, 2022 12:02 PM

      The things they are doing with cereal these days!

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      March 22, 2022 12:32 PM

      This is sick, thanks

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      March 22, 2022 12:36 PM

      Are there benefits to using this with a Gsync monitor?

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        March 22, 2022 2:02 PM

        For games where your GPU can run far in excess of your max refresh rate, yes. Like in my example with Hollow Knight in the article. I'm getting the input latency of 400fps at 100hz vsynced.

        For games where your GPU more fully loaded and going above and below max refresh, I'm not sure. Last I heard, Nvidia recommends you enable vsync in Nvidia CP in combination with Gsync. I imagine that configuration doesn't add extra input latency, though I don't know for sure. If that's the case, applying any type of frame cap or vsync from Special K would be redundant.

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          March 22, 2022 2:08 PM

          And also, if your Gsync monitor also has a BFI mode that you want to use, you'd want to use some form of vsync during that, so this would be good.

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      March 22, 2022 12:43 PM

      So is this even better than using RTSS for fps limiting? I've heard Special K mentioned once but never really looked into it.

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        March 22, 2022 12:54 PM

        I think this is basically what I'm asking too.

        There is a lot of info here but I need a TLDR

        Also can I use this on steam deck?

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          March 22, 2022 2:03 PM

          I don't think there is a Linux version.

          And the steam deck is fixed refresh 60hz. So the only frame cap you'd ever want to use would be 30 or 60. Nothing in between would look good.

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            March 22, 2022 2:04 PM

            And Steam Decks 30fps limiter is apparently super smooth. Way smoother than the limiter in most games.

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      March 22, 2022 1:53 PM

      SpecialK works well for Elden Ring if you want to play at 100 FPS or higher, or have HDR in windowed mode.

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        March 22, 2022 2:07 PM

        Do you also get banned from playing online?

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          March 22, 2022 2:10 PM

          Easy anti-cheat blocks Special K in a lot of games, but not sure about Eldin Ring

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          March 22, 2022 2:25 PM

          You are blocked while you run it. However, it doesn't modify game files. You start the game via SpecialK, so you can always start the game via Steam instead to use MP features. I bounce back and forth.

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      March 22, 2022 2:33 PM

      Rather still use RTSS with Scanline-Sync: way easier to set up, less hooks, supports Vulkan and is whitelisted by a bunch of anti-cheat software.

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