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G-SYNC questions
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Darren Hodgson
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Default G-SYNC questions - 06-04-2017, 19:01 | posts: 14,915 | Location: England

I have just got a new G-SYNC monitor this weekend and while it seems to be working great so far (very impressive technology, I must say) I admit that I am a bit confused about some things such as:

1. I disabled v-sync in the games but many were already running up to 165 fps so can I leave it on or does it have to be disabled for G-SYNC to work? Or does G-SYNC override the v-sync setting if it is enabled?

2. Does G-SYNC work with UWP games like Forza Motorsport 6 APEX because that does not have an option to disable v-sync? It ran over 100 fps in places (at 4K!) but the experience felt disappointing as there was stuttering.

I loaded up Forza Horizon 3 and turned off v-sync in that game and that felt absolutely fine even though the framerate was anywhere between 65 and 135 fps (again at 4K). There is a framerate limiter in that game but it seems to be bugged since it shows not just 165 fps but 33 fps, 41 fps, 55 fps and 83 fps! Not sure why that is, I was expected standard settings such as 60, 120 and 144!

3. Can you set the framerate cap in a game to, say, 120 fps, and enable v-sync on these monitors and still have a smooth experience even if the framerate drops below 120 fps. Or do you set 120 fps and disable v-sync so that G-SYNC can work properly. There is a Turbo button on the monitor that toggles between 60, 120 and 165 Hz so is that a better way to cap framerates?

I don't necessary want to run a game at 165 fps but, say, 90 or 120 fps. This reduces heat and also makes my overclock potentially more stable. Can you do that with G-SYNC?
   
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Default 06-04-2017, 21:10 | posts: 1,095 | Location: England

Here's how i have mine setup.

V-Sync on in control panel, 97fps cap globally using Rivatuner (100Hz monitor) and V-Sync disabled in game.

If you run games with V-Sync enabled with no fps cap then once your fps hits the monitors refresh rate V-Sync will enable causing input lag, if you disable V-Sync then G-Sync disengages above your monitors refresh rate and causes screen tearing.

So i just leave V-Sync enabled globally (G-Sync just feels better with it on for some reason) and cap the fps just below my refresh rate to keep G-Sync enabled at all times.

G-Sync does work with Windows Store games but yeah, fps caps are broken in some games.

Hope that helps.
   
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Default 06-04-2017, 22:39 | posts: 1,153

To make sure g-sync is always active, make sure you know what refresh rate the game has picked. It's best to always force the maximum your monitor supports (in the nvidia panel in 3D settings, "Preferred refresh rate" should be globally set to "highest available.")

Then, make sure to cap your frame rate to AT LEAST 2FPS below the max refresh. I use 4FPS lower to be 100% safe. It's best to use the game's built-in frame rate limiter. If the game doesn't have one (or if it sucks,) next best thing is RTSS.

If the game is rather "heavy", meaning FPS is fluctuating wildly (like 60FPS min and 140FPS max), then it might be better to cap much lower (like 90FPS), to make things more consistent.

For games where you don't want to get very high framerates you should still make sure the highest refresh rate is used (144Hz or 165Hz in your case), but cap to 60FPS, 75FPS, or something like that. This gives you the same smoothness and tear-free image as vsync, but unlike vsync, there's almost no input lag. Do not use 60Hz mode for 60FPS games. Always use the max refresh and cap your FPS to what you want! (The reason is that this makes sure g-sync is active, and you get lower input lag because the screen is updated faster in higher refresh modes.) Check the monitor's OSD to make sure 144Hz/165Hz is active.

Rules of thumb:
  • Always disable vsync in-game. This avoids issues with games that try to do vsync frame-pacing and result in heavy stutter (like Fallout 4, where you need to disable vsync in an ini file,) or games that enable triple buffering with vsync (g-sync works best with double-buffering.)
  • Enable v-sync globally in the nvidia panel. This does not add any input lag (if you don't reach the max refresh, which is why you cap your FPS), but makes sure a special anti-tearing function of g-sync is enabled (it's for when frame times are unstable; in that case, you can get tearing even with low FPS.)
  • When you change the g-sync configuration in the nvidia panel, this will reset the vsync setting back to "use application setting". You need to change it back to "On" every time you change g-sync settings.
  • Setting "maximum pre-rendered frames" to 1 will reduce input lag when your frame rate cannot reach the cap.

More details here:

http://www.blurbusters.com/gsync/gsync101-range/

And MUCH more details here:

http://forums.blurbusters.com/viewtopic.php?f=5&t=3073

It looks a bit complicated at first, but really, it's just about understanding that g-sync has a frame rate range it can work in (0FPS up to max refresh - 2FPS,) and that you need to stay within that range to benefit from it.

Last edited by RealNC; 06-04-2017 at 23:09.
   
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Default 06-05-2017, 00:35 | posts: 14,915 | Location: England

Thanks for the replies, guys.

I didn't know V-Sync had to be enabled globally but it does explain why I was seeing higher framerates than the max. refresh rate of 165 Hz in games such as FIFA 17 (even at 4K with 4xMSAA the game runs between 100 and 230 fps but oddly I did not notice any screen tearing above 165 fps!!!) and Mafia III (where the game was tear-free but there was horrid tearing in the menus only fixable by enabling in-game v-sync. Not only that but the camera is extremely twitchy which I do not recall before... is this a bug with G-SYNC?).

How does forcing V-Sync globally affect benchmarking programs? For example, Unigine Heaven 4.0 at 1080p and no AA runs well above 165 fps. Wouldn't forcing V-Sync globally artificially cap these programs at 165 fps?

It's a shame that G-SYNC doesn't just automatically enable v-sync above the refresh rate without having to force it globally. My understanding from reading is that this is how it used to work but NVIDIA changed it last year for some reason.
   
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Default 06-05-2017, 00:45 | posts: 1,153

Yes, vsync used to be always on. NVidia added a way to disable it due to popular request.

The twitchy controls have probably nothing to do with g-sync directly, but are the result of the high framerate and low input lag. You should probably lower your mouse sensitivity ;-)

Note: you still need to cap your frame rate. It doesn't matter if you enable vsync or not. When you reach 163FPS, g-sync gets disabled. If you see 164 or 165FPS, that means you're playing with vsync, not g-sync. The article I linked to explains this.
   
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Darren Hodgson
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Default 06-05-2017, 01:15 | posts: 14,915 | Location: England

Thanks RealNC. I will check your links now.

*EDIT*
Thanks for the links in the G-SYNC questions thread. I think I understand how it works a bit better and decided rather than force v-sync globally in the NVIDIA profile (which could cause issues with some games or applications) then I will instead use RTSS to cap any games where the framerate exceeds the refresh rate of the display.

As such I've capped both FIFA 17 and Mafia III at 160 fps (the latter shows massive screen tearing in the menus due to the framerate being 230+ fps but the game itself never comes close to exceeding 165 fps). I think that is the best method personally as most new games will never go over 165 fps, not on the settings I like to use anyway ( ) and I can just enabled v-sync in the game for older titles and put up with a bit of extra input lag (not that I can notice it at 165 fps!).

Really love G-SYNC so far and wonder how I ever got by without it!

Last edited by Darren Hodgson; 06-05-2017 at 09:57.
   
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Default 06-05-2017, 15:59 | posts: 9,604 | Location: USA

Quote:
Originally Posted by Darren Hodgson View Post
Thanks for the links in the G-SYNC questions thread. I think I understand how it works a bit better and decided rather than force v-sync globally in the NVIDIA profile (which could cause issues with some games or applications) then I will instead use RTSS to cap any games where the framerate exceeds the refresh rate of the display.
You need to enable Vsync in NVCPL to eliminate tearing.
There will be no issues caused in any games from that.

Make sure in game is turned off and NVCPL is on.
   
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Darren Hodgson
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Default 06-05-2017, 19:44 | posts: 14,915 | Location: England

Quote:
Originally Posted by Agent-A01 View Post
You need to enable Vsync in NVCPL to eliminate tearing.

There will be no issues caused in any games from that.

Make sure in game is turned off and NVCPL is on.
This is what confuses me.

My understanding is that there is NO tearing with v-sync on UNLESS the game's frame rate exceeds the refresh rate, whether that's 60, 120, 144 or 165 Hz.

The choice is either cap the games that run above the refresh rate or force v-sync on globally. The advantage of using the former is that benchmarks will not be artificially limited to the maximum refresh rate and the advantage of the latter is that you don't have to worry about capping framerates on a per-game basis or experiencing any screen tearing.

I will try forcing v-sync on in the global profile as you suggest for now but if this is the suggested setting then why isn't it set to that by default in the control panel when a G-SYNC monitor is detected. Surely, most people would rather have no tearing at all; after all that is the primary reason for buying a G-SYNC monitor in the first place!
   
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Default 06-05-2017, 19:57 | posts: 9,604 | Location: USA

VSYNC ON caps FPS at refresh rate, which in turn disables Gsync functionality.

With Vsync Off you will still get minor tearing(i won't go into the technical details but that's how it works).

So that is the point of FPS cap 2-3fps below with VSync ON to ensure that tearing is fixed and that gsync stays active all the time.
Vsync is not ON unless FPS = refresh rate.

So to be clear.

Set VSync ON with FPS cap with ingame(or rtss if no ingame) to ~3fps below refresh rate.

This is the most optimal setup.

Btw Vsync is set to app controlled because not everybody has a gsync monitor and even if they did, not everyone knows to set a FPS cap either.

Originally Gsync had VSync enabled by default but people were complaining about the FPS being capped so they separated the options.
   
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Darren Hodgson
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Default 06-05-2017, 23:32 | posts: 14,915 | Location: England

@ Agent-A01 - Thanks for the reply.

And, yes, I know why v-sync is set to application controlled by default for everyone else but the control panel clearly detects G-SYNC as it gives the additional settings so why don't NVIDIA set the default to on for v-sync when such displays are detected?

*EDIT*
Ah, OK, so people complained about it. Typical.

I mean if you and RealNC had not explained all this to me then I might have thought my monitor was faulty on seeing screen tearing when G-SYNC is enabled. I mean Mafia III ran fine in game when I played it yesterday because it ran well under 165 fps but I thought something was wrong when paused the game and scrolled through the menu. The tearing was horrendous but I realised that was because the framerate was over 200 fps and that v-sync was disabled globally at that time.

Anyway, I have enabled v-sync globally as suggested and games appear to be running as before with a refresh rate of up to 165 fps. I found out that there is not only a refresh rate OSD counter built into my monitor but also that the NVIDIA control panel has a G-SYNC indicator which shows only when G-SYNC is active.

I played FIFA 17 earlier; it loaded at 60 fps with G-SYNC off then once in the menus it switched to 165 fps with G-SYNC off. At first I thought it was odd but ingame it runs at 165 fps and the G-SYNC indicator shows. Oddly, the G-SYNC indicator disappears during replays and cutscenes which is when the framerate drops below 165 fps to 90 - 120 fps. The refresh rate onscreen still shows 165 Hz though but the framerate per RTSS is 90 - 120 fps. Is that normal? Do you know why is G-SYNC disabled for the replays and cutscenes? I played Assassin's Creed: Unity later on and G-SYNC was enabled at all time in that game although it never ran at anywhere near 165 fps.

I've also been trying to play Tom Clancy's Division but it is loading up windowed with the DX12 setting from last time I played it. If I change the setting to Fullscreen and hit Apply then the game crashes every time. It has never crashed before. I've just verified the files and Uplay reports it was successful. I will try it again now.
   
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Darren Hodgson
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Default 06-07-2017, 12:58 | posts: 14,915 | Location: England

I've one last question regarding the v-sync setting in the control panel: is there any disadvantage to say forcing V-Sync to Fast rather than On globally?

This would presumably allow games and benchmarks to run above the refresh rate of the display, 165 Hz, without any screen tearing. V-Sync = On obviously caps the framerate to 165 fps and V-Sync = Off results in horrendous screen tearing.
   
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Default 06-07-2017, 14:18 | posts: 4,876 | Location: Sweden

Quote:
Originally Posted by Darren Hodgson View Post
I have just got a new G-SYNC monitor this weekend and while it seems to be working great so far (very impressive technology, I must say) I admit that I am a bit confused about some things such as:

1. I disabled v-sync in the games but many were already running up to 165 fps so can I leave it on or does it have to be disabled for G-SYNC to work? Or does G-SYNC override the v-sync setting if it is enabled?

2. Does G-SYNC work with UWP games like Forza Motorsport 6 APEX because that does not have an option to disable v-sync? It ran over 100 fps in places (at 4K!) but the experience felt disappointing as there was stuttering.

I loaded up Forza Horizon 3 and turned off v-sync in that game and that felt absolutely fine even though the framerate was anywhere between 65 and 135 fps (again at 4K). There is a framerate limiter in that game but it seems to be bugged since it shows not just 165 fps but 33 fps, 41 fps, 55 fps and 83 fps! Not sure why that is, I was expected standard settings such as 60, 120 and 144!

3. Can you set the framerate cap in a game to, say, 120 fps, and enable v-sync on these monitors and still have a smooth experience even if the framerate drops below 120 fps. Or do you set 120 fps and disable v-sync so that G-SYNC can work properly. There is a Turbo button on the monitor that toggles between 60, 120 and 165 Hz so is that a better way to cap framerates?

I don't necessary want to run a game at 165 fps but, say, 90 or 120 fps. This reduces heat and also makes my overclock potentially more stable. Can you do that with G-SYNC?
Hey Darren.

Regarding Forza Horizon 3, I've had huge problems making it run fine and finally gave up and just play it on my 4K TV. Same thing with Diablo 3 and also with HotS. I don't know why but there are games that do not like G-sync and it's simply impossible to make them run smoothly as you'd expect at 85-144fps. Forza for example ran at 90 something with my old 1080 but it stuttered like hell. I had to try several different things and finally settled for ULMB which worked OK. This actually also applied to D3 which seems impossible to play stutter free for some odd reason.

Like you've noticed - If you are playing a game with V-sync disabled and that game exceeds 144fps the game will start tearing. This is why I enable it in those games where I know the FPS will cap. Some have mentioned limiting the FPS and I have only tried it in Skyrim which completely broke the game but I assume it works better in other games.

A final note regarding FH3, the game doesn't run in Fullscreen (it looks like it but it's borderless windowed) so this means that G-sync doesn't kick in unless you've enabled G-sync in Fullscreen and Windowed (NVCPL). My personal experience is that G-sync doesn't work very well in Windowed. It's been some time since I played with that setting but WoW in Borderless Windowed plus G-sync Windowed works really bad (extremely low FPS). Maybe I'm doing something wrong but you could take this into account while testing.
   
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Darren Hodgson
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Default 06-07-2017, 14:29 | posts: 14,915 | Location: England

@ Netherwind - Thanks for your post.

To clarify though, it is the free Forza Motorsport 6 APEX which doesn't run well with G-SYNC on my PC not Forza Horizon 3 (that runs fine).

Also, I do have G-SYNC enabled for both fullscreen and windowed applications as I was aware that there are not only UWP games which run using borderless window mode but also Unity Engine ones too (which annoyingly don't support higher than native resolutions via DSR either).

I haven't tried any Unity games with G-SYNC enabled yet though but, in a way, borderless window kind of behaves like G-SYNC anyway, allowing games to run at higher than refresh rate framerates without any screen tearing so maybe that's why G-SYNC doesn't play well with it since they are both trying to do basically the same thing?
   
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Default 06-07-2017, 18:09 | posts: 1,153

Quote:
Originally Posted by Darren Hodgson View Post
I haven't tried any Unity games with G-SYNC enabled yet though but, in a way, borderless window kind of behaves like G-SYNC anyway, allowing games to run at higher than refresh rate framerates without any screen tearing so maybe that's why G-SYNC doesn't play well with it since they are both trying to do basically the same thing?
No. Borderless windowed works like fast sync. It does not synchronize the monitor to the game's frame rate. It eliminates tearing, but it does not eliminate stutter. Also, compared to fast sync, it adds input lag.
   
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Default 06-07-2017, 19:05 | posts: 1,190 | Location: Greece

My thinking..> if you already have limit your fps lower from your refresh rate (no matter if cap will be 3 or 30 or even more fps lower than refresh rate, e.g. ref/rate 144 with cap @100) why is there even one reason to have Vsync ON in NVCL...? fps won't get more than your cap so having Vsync on or whatever it simply WON'T matter..

TLTR..with fsp limiter there isn't any reason for having Vsync on.
   
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Darren Hodgson
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Default 06-07-2017, 19:55 | posts: 14,915 | Location: England

Quote:
Originally Posted by CK the Greek View Post
My thinking..> if you already have limit your fps lower from your refresh rate (no matter if cap will be 3 or 30 or even more fps lower than refresh rate, e.g. ref/rate 144 with cap @100) why is there even one reason to have Vsync ON in NVCL...? fps won't get more than your cap so having Vsync on or whatever it simply WON'T matter..

TLTR..with fsp limiter there isn't any reason for having Vsync on.
I saw someone post a link of a game showing screen tearing with G-SYNC enabled and v-sync off globally and in the game even though the framerate was below the max refresh rate of the screen. Forcing v-sync on fixes it. The tear occurred near the bottom of the screen.

I'm not sure how old that video was though; it may have been an early bug with G-SYNC that has now been fixed. You don't have to force v-sync but if you don't then you will get screen tearing above the max refresh rate of the screen. I've seen this myself in Mafia III's menu's. It didn't happen in FIFA 17 though despite running at 220 FPS.
   
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Default 06-07-2017, 20:22 | posts: 1,153

Quote:
Originally Posted by CK the Greek View Post
My thinking..> if you already have limit your fps lower from your refresh rate (no matter if cap will be 3 or 30 or even more fps lower than refresh rate, e.g. ref/rate 144 with cap @100) why is there even one reason to have Vsync ON in NVCL...? fps won't get more than your cap so having Vsync on or whatever it simply WON'T matter..

TLTR..with fsp limiter there isn't any reason for having Vsync on.
The vsync setting is tied to a g-sync function that compensates unstable frame times. Without it, you can get tearing even when your FPS is within g-sync range.

This is usually the result of frame limiters that are not able to output consistent frame times. CS:GO is an example. On many systems (mine included), there is full-on tearing even with a frame cap of 120FPS (fps_max 120) on 144Hz.

Another example is games that have severe hitching in some occasions, like open world games (Fallout 4, Skyrim, etc) that for very brief moments have frame rates that fall as low as 20FPS (or even lower!) while loading new assets. It's not limited to open-world games, obviously. Any game with hitching issues can produce very unstable frame times and thus tear (Deus Ex MD is an example.) Frame times are fluctuating wildly during those moments, and thus you get tearing momentarily.

Enabling v-sync allows the g-sync module to compensate for such inconsistent frame times. It delays a frame just long enough so that the tear line is hidden (it's put outside the visible region of the screen; it's displayed during the vertical blanking period of the current refresh cycle.)

The core issue is that g-sync cannot drive the monitor with vastly different timing between adjacent frames in rapid succession. I don't know why, but I suspect it's due to overdrive. The pixels need at least some time to change their colors and if you don't give them that time, you are going to get flicker. So if the frame times are too messed up, then g-sync has to either tear, or delay the frame long enough to avoid the tear.

The mechanism of delaying a frame just a bit, long enough to avoid the tear is controlled by the v-sync setting. It has no negative side-effect when that compensation is not needed. So it doesn't hurt to enable it. Which is why it's the recommended setting.

RTSS does not have that problem (it has extremely well paced frame timing.) When using RTSS to limit the frame rate, and the game does not have severe hitching issues, then v-sync off + g-sync is not going to tear. But the bottom line is: you don't gain anything from using v-sync off. So why disable it?

Last edited by RealNC; 06-07-2017 at 20:29.
   
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Default 06-08-2017, 04:04 | posts: 1,967 | Location: Calgary Canada®

What are your folk's thoughts on setting Vsync to "Fast" instead of regular Vsync globally?
   
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Darren Hodgson
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Default 06-08-2017, 07:04 | posts: 14,915 | Location: England

I tried setting Fast globally last night and loaded up FIFA 17, which runs at about 220 fps during gameplay on my system even though it's set to 4K with 4xMSAA! Anyway, the game felt perceptibly stuttery me (maybe I was imagined it though it knowing that I had forced the Fast setting?) whereas the day before with v-sync set to Off in the global profile it ran really smoothly and I didn't even notice any screen tearing at all (I am very sensitive to it so if it was there I should have seen it).

I think I'm going to have to experiment a bit more with the setting but I did find a customer help support question to NVIDIA about using Fast with G-SYNC and they actually said it was fine so if you like your games to run as fast as possible and prefer having a little stutter to seeing screen tearing then it's perhaps the better setting to use. Also, it will have less impact on benchmark programs than v-sync = on as they will still be able to run uncapped.
   
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Mr_ALLroy
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Default 06-08-2017, 07:27 | posts: 1,967 | Location: Calgary Canada®

I just tried fast sync w/ g-sync in BF1. Earlier, I had V sync set to "let program decide" and it was noticeably choppy. I think with some games, I might just have to tweak the individual game profile in the Nvidia drivers apart from the global settings.
   
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Netherwind
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Default 06-08-2017, 15:04 | posts: 4,876 | Location: Sweden

Quote:
Originally Posted by Darren Hodgson View Post
@ Netherwind - Thanks for your post.

To clarify though, it is the free Forza Motorsport 6 APEX which doesn't run well with G-SYNC on my PC not Forza Horizon 3 (that runs fine).
Funny, for me it was the opposite Apex ran perfectly and FH3 didn't. But it's been a while since I did the testing.
   
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RealNC
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Default 06-09-2017, 05:16 | posts: 1,153

Quote:
Originally Posted by Mr_ALLroy View Post
I just tried fast sync w/ g-sync in BF1. Earlier, I had V sync set to "let program decide" and it was noticeably choppy.
In-game vsync OFF, control panel vsync ON.

The game should think it runs without vsync (because that's the whole point of g-sync.) Usually it's OK to use in-game vsync ON, but not always.
   
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