Placebo about input lag ?

Talk about NVIDIA G-SYNC, a variable refresh rate (VRR) technology. G-SYNC eliminates stutters, tearing, and reduces input lag. List of G-SYNC Monitors.
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del1ks
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Placebo about input lag ?

Post by del1ks » 04 Jun 2019, 09:40

Hello,

Sorry for my english it's not my native language.

I have two g-sync monitors (aw2518h and xb271hu). I'll start by saying tearing never bothered me, I can see it, but I don't find it that annoying. (So maybe g-sync is just useless for me ?) I'm a PC gamer since 1995 and played a lot of 1.6 and CSS competitively and I guess I'm kind of used of the feeling of having really high framerate.

I don't play that much of competitive game these days except Apex Legends, so I'm mostly talking about slower single player experience. I want to like g-sync, because when I compare I can absolutely see the difference in motion, it looks a little better with g-sync to my eyes (remember, tearing is not a big no for me, but I do like the stutter free motion) BUT I'm pretty sure I can always feel the added input lag. I talked about placebo in my title because you guys here are saying if done properly it shouldn't be slower, and I trust you. (Thank you for being you, read the g-sync 101 article like three times and it's a pleasure to read you Chief, jorimt and of course all the community).

I'm not even comparing a game with uncapped +300 fps vs capped g-sync 241 fps, but even a game with lower framerate like between 60 and 120, it feels so slow to my eyes with g-sync.I played yesterday RE2 remake (crazy good game), and yea it seems so much faster with g-sync off, but still this game is knows for having some issue with negative mouse acceleration, so yea maybe it can skew the result...

I tried every settings, g-sync ON + vsync ON, g-sync + vsync OFF, I use RTSS limiter, I tried to use frame limiter in game if there is one, and it feels so sluggish everytime when I use g-sync.

It's not crazy input lag like v-sync (any game is literally unplayable for me with v-sync) but I still can feel it. Maybe someone have an idea what it could be ? I do use the best recommended settings, tried different max prerendered frame.

It's been some time since I did a clean reinstall of Windows 10 so I'll probably do that in some days, but there is probably nothing wrong since I keep my computer clean, it's just for the psychological aspect.

Maybe the "syncing" feeling isn't just for me, if that make sense.

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RealNC
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Re: Placebo about input lag ?

Post by RealNC » 04 Jun 2019, 10:14

VRR will force the worst-case input latency to be equal to the display scanout latency. At 100FPS for example, if you move the mouse just as the monitor is starting to scan out a new frame, your input will show on the screen 10ms later (because one frame at 100FPS takes 10ms to scan out.) At 60FPS, it would need 16.7ms.

However, when you use the same FPS capping method in both cases, then the average latency is still nearly identical though, so it should "feel" just about the same. Maybe it's the tearing that makes it feel snappier to your eyes. Sudden inputs result in sudden tearing, and the lack of that could be associated with a lack in responsiveness if you're not used to playing tear-free.

In my own experience, when playing with g-sync ON vs OFF while using the same FPS cap method (and vsync OFF in both cases), I would sometimes think that I feel some extra latency with g-sync. But then if I disable g-sync and try the same thing again in the game, I realize that it's the same. Whatever latency I could feel was there did not go away without g-sync OFF. It wasn't g-sync that caused it. When I first got a g-sync display, I would do this test many times. In the end it always turned out that g-sync had nothing to do with the latency I could feel. It was just the FPS drops due to the GPU being maxed out.

As a test, try a game that normally gives you 120+ FPS all the time guaranteed (lower the in-game graphics details if you have to.) Then cap that game to 90FPS and compare g-sync OFF vs ON. In my case, I can't feel any difference. If the game however ends up maxing out the GPU and it falls below 90FPS, then input lag is going to increase and is rather easily felt with mouse-driven games. However, this also happens with g-sync OFF. Maybe that's what you're seeing.

These are my theories, at least. I'm not a human vision scientist :P
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Chief Blur Buster
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Re: Placebo about input lag ?

Post by Chief Blur Buster » 04 Jun 2019, 11:02

241fps for 240Hz?

You have to cap below, not above, when you're capping G-SYNC. Cap to 235 or thereabouts. 241 will add extra lag to GSYNC+VSYNC ON when framerates start hitting equal refresh rate.
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del1ks
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Re: Placebo about input lag ?

Post by del1ks » 04 Jun 2019, 11:03

Yes sorry, thinking of 141, when I use my 240 I cap to 237

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Last edited by del1ks on 05 Jun 2019, 02:27, edited 1 time in total.

del1ks
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Re: Placebo about input lag ?

Post by del1ks » 04 Jun 2019, 11:05

RealNC wrote:VRR will force the worst-case input latency to be equal to the display scanout latency. At 100FPS for example, if you move the mouse just as the monitor is starting to scan out a new frame, your input will show on the screen 10ms later (because one frame at 100FPS takes 10ms to scan out.) At 60FPS, it would need 16.7ms.

However, when you use the same FPS capping method in both cases, then the average latency is still nearly identical though, so it should "feel" just about the same. Maybe it's the tearing that makes it feel snappier to your eyes. Sudden inputs result in sudden tearing, and the lack of that could be associated with a lack in responsiveness if you're not used to playing tear-free.

In my own experience, when playing with g-sync ON vs OFF while using the same FPS cap method (and vsync OFF in both cases), I would sometimes think that I feel some extra latency with g-sync. But then if I disable g-sync and try the same thing again in the game, I realize that it's the same. Whatever latency I could feel was there did not go away without g-sync OFF. It wasn't g-sync that caused it. When I first got a g-sync display, I would do this test many times. In the end it always turned out that g-sync had nothing to do with the latency I could feel. It was just the FPS drops due to the GPU being maxed out.

As a test, try a game that normally gives you 120+ FPS all the time guaranteed (lower the in-game graphics details if you have to.) Then cap that game to 90FPS and compare g-sync OFF vs ON. In my case, I can't feel any difference. If the game however ends up maxing out the GPU and it falls below 90FPS, then input lag is going to increase and is rather easily felt with mouse-driven games. However, this also happens with g-sync OFF. Maybe that's what you're seeing.

These are my theories, at least. I'm not a human vision scientist :P
Thank you for your explanation. Maybe it's just a feeling it's possible. I know a friend who absotulety can't play without vsyc, saying it's a stuttery mess without it. Maybe I should give him one of my gsync monitor [RELIEVED FACE]

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Kyneaz
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Re: Placebo about input lag ?

Post by Kyneaz » 04 Jun 2019, 11:30

Hi, i have myself a g-sync monitor (PG248Q) and i can say that what you are experiencing is not a placebo.
I play black ops 4, apex with my fps capped at 172fps (my monitor is 180hz)
and i can feel the difference between G-sync on + NVP Vsync on against Vsync off (both still capped at 172fps)

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Re: Placebo about input lag ?

Post by Chief Blur Buster » 04 Jun 2019, 15:10

Kyneaz wrote:And i can feel the difference between G-sync on + NVP Vsync on against Vsync off (both still capped at 172fps)
Try out an in-game framerate cap instead of NVCP. I've seen NVCP capping add more lag, though more recent tests needs to bear this out.
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Re: Placebo about input lag ?

Post by Kyneaz » 04 Jun 2019, 17:11

Chief Blur Buster wrote:
Kyneaz wrote:And i can feel the difference between G-sync on + NVP Vsync on against Vsync off (both still capped at 172fps)
Try out an in-game framerate cap instead of NVCP. I've seen NVCP capping add more lag, though more recent tests needs to bear this out.
But if i disable NVCP Vsync, tearing is not supposed to appear at the bottom of the display ?

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Re: Placebo about input lag ?

Post by RealNC » 04 Jun 2019, 17:33

That's a miscommunication from Chief. He thought you're using nvidia inspector to enable the nvidia frame limiter.
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