Fast sync and variable refresh rate together?

Necrosaro

Active Member
As the title says should fast sync in Nvidia drivers be on with variable refresh rate also being on in windows or just one of them on?

I have a Nvidia 1070 for reference and is mostly used for movies/tv shows and a little splash of gaming mixed in. The games I do play are not demanding however.
 
BlurBusters is a good resource for monitor-related stuff, however they're extremely technical and so you can leave with more questions than when you started. Here's my summary, but I can go into more detail if needed:

FastSync and G-Sync are compatible, because they work in different ways. FastSync is a GPU feature that caps your frame rate to your monitor's maximum refresh rate, and then drops extra and unfinished frames to help reduce screen tearing. G-Sync is a monitor feature that dynamically adjusts a monitor's refresh rate to match a game's current frame rate when it drops below the monitor's maximum refresh rate, reducing screen tearing. In other words, FastSync works on the upper end of frame rates, while G-Sync works on the lower end of frame rates.

Using both technologies is likely okay for almost everyone, except for twitchy shooters, in which case I'd turn off FastSync and instead just cap my frame rates via the game's cfg file, to a manually optimized number based on things like my frame rate lows/highs in that specific game. Also on that note, G-sync wouldn't be necessary in a game that has consistently high frame rates since the feature automatically disables itself whenever the frame rates go above the monitor's maximum refresh rate--if you have a fancy G-Sync monitor, it's not helping you play Counter Strike Go with 600 frames per second, as the G-sync feature is disabled in that case. FastSync would do something though, and it would cap that 600 frames down to 240 or whatever the monitor's maximum refresh rate is, while working to reduce screen tearing too.
 
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Sorry, I just realized you specifically meant the Windows setting for "variable refresh rate", my brain just assumed you meant G-Sync/FreeSync. I left my other post since it's still helpful information for lurkers and such.

That "variable refresh rate" Windows setting was added to support UWP apps, which weren't playing nice with the already established standards (Vsync/G-Sync/etc). Like with anything "gaming" that Microsoft pushes, I'd just test it yourself to know for sure, because this stuff never turns out to be as good as it's made out to be, or there's some catch. It shouldn't conflict with something like G-sync or FastSync though, since it's basically a toggle for "Allow UWP apps to use Vsync and other similar technologies" and the setting literally only appears visible if your system supports having it enabled.

Me personally, I'd leave it disabled until I come across an app that doesn't work as expected (unlikely unless you use Microsoft Store often) as this is often the path of least resistance in operating systems to reduce bugs and other quirks, while we wait for features like these to mature. Microsoft still has to individually patch every UWP app to make them compatible with this setting too. Here's a direct quote from Microsoft about this feature and is an example of why I always take Microsoft's "gaming" features with a grain of salt:

The company explains that the feature "is a significant and fundamental change to the driver model" and compares it to "rebuilding the foundation of a house while still living in it". This is why stuff like Game Mode had problems, because Microsoft likes to try and work backwards, rather than build from the ground up around established standards.
 
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BlurBusters is a good resource for monitor-related stuff, however they're extremely technical and so you can leave with more questions than when you started. Here's my summary, but I can go into more detail if needed:

FastSync and G-Sync are compatible, because they work in different ways. FastSync is a GPU feature that caps your framerate to your monitor's maximum refresh rate, and then drops extra and unfinished frames to help reduce screen tearing. G-Sync is a monitor feature that dynamically adjusts a monitor's refresh rate to match a game's current framerate when it drops below the monitor's maximum refresh rate, reducing screen tearing. In other words, FastSync works on the upper end of framerates, while G-Sync works on the lower end of framerates.

Using both technologies is likely okay for almost everyone, except for twitchy shooters, in which case I'd turn off FastSync and instead just cap my framerates via the game's cfg file, to a manually optimized number based on things like my framerate lows/highs in that specific game. Also on that note, G-sync wouldn't be necessary in a game that has consistantly high framerates since the feature automatically disables itself whenever the framerates go above the monitor's maximum refresh rate--if you have a fancy G-Sync monitor, it's not helping you play Counter Strike Go with 600 frames per second, as the G-sync feature is disabled in that case. FastSync would do something though, and it would cap that 600 frames down to 240 or whatever the monitor's maximum refresh rate is, while working to reduce screen tearing too.
I don't have gsync or a gsync capable monitor(I use a LG C7).

Haha looks like we posted around the same time haha

After reading your post why I enabled it was because it offered better movie frames. Just trying to figure out what is causing the very minor issue of the odd (feels like a drop in frames or slight ghosting((very hard to explain)) but tested and the program shows it doesn't drop the frames when it happens. It happens more when I remove Xbox from NTLITE (I know it's super weird) so I leave Xbox alone.

I also don't use any of the tvs motion smoothing settings as a heads up

Movie playing program is Smplayer which provides me with the best movie experience out of all I have tried.
 
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When you say "better movie frames" do you mean smoother, or higher frames? More smoothness could make sense, but higher frame rates would be impossible since Vsync and FastSync are frame-limiting features. Most movies are coded at very low frame rates too (24-30 fps) and shouldn't be playing back at a speed other than what they were filmed at.

Over the years most movie-related issues I've come across have all been related to the program used to view them, and fixing it usually meant changing a setting in that app. A lot of movie players for example have various settings that drop frames to keep audio/video in sync. Does the same issue exist if you use something like VLC for a comparison test?

LG C7 doesn't support variable refresh rate so turning on Windows VRR shouldn't do anything positive since the television can't make use of it, and movie players and TVs should also be ignoring features like FastSync, Vsync, and G-Sync anyway since film is a completely different animal than games are. I did some Googling on this television and it sounds like maybe the issue you're experiencing is a problem stemming from OLED technology.

One of the links I found said you can potentially fix the problem on an LG C7 by adjusting settings on the TV itself: "To be able to display 24p content without judder, the 'TruMotion' option must be set to 'User' and both the 'De-Judder' and 'De-Blur' sliders set to zero (when set to 0, no soap opera effect will be added)." Here's some other relevant links:

https://www.rtings.com/tv/reviews/lg/c7-oled
https://www.reddit.com/r/OLED/comments/os55tx/did_my_c7_handle_24p_content_better_than_my_c1/
https://www.reddit.com/r/OLED/comments/8g01j3/netflix_judder_on_netflix_hdr_content_with_lg_c7/
https://www.reddit.com/r/OLED/comments/8foms9/goig_crazy_with_stutter/
 
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When you say "better movie frames" do you mean smoother, or higher frames? More smoothness could make sense, but higher framerates would be impossible since Vsync and FastSync are frame-limiting features. Most movies are coded at very low framerates too (24-30 fps) and shouldn't be playing back at a speed other than what they were filmed at.

Over the years most movie-related issues I've come across have all been related to the program used to view them, and fixing it usually meant changing a setting in that app. A lot of movie players for example have various settings that drop frames to keep audio/video in sync. Does the same issue exist if you use something like VLC for a comparison test?

LG C7 doesn't support variable refresh rate so turning on Windows VRR shouldn't do anything positive since the television can't make use of it, and movie players and TVs should also be ignoring features like FastSync, Vsync, and G-Sync anyway since film is a completely different animal than games are. I did some Googling on this television and it sounds like maybe the issue you're experiencing is a problem stemming from OLED technology.

One of the links I found said you can potentially fix the problem on an LG C7 by adjusting settings on the TV itself: "To be able to display 24p content without judder, the 'TruMotion' option must be set to 'User' and both the 'De-Judder' and 'De-Blur' sliders set to zero (when set to 0, no soap opera effect will be added)." Here's some other relevant links:

https://www.rtings.com/tv/reviews/lg/c7-oled
https://www.reddit.com/r/OLED/comments/os55tx/did_my_c7_handle_24p_content_better_than_my_c1/
https://www.reddit.com/r/OLED/comments/8g01j3/netflix_judder_on_netflix_hdr_content_with_lg_c7/
https://www.reddit.com/r/OLED/comments/8foms9/goig_crazy_with_stutter/
Thanks for trying to help here...

With movies running at 24p cannot gain frames naturally but it's really hard to explain unless you see it with your own eyes.

Things got better after getting pretty well everything removed from that I wanted from windows 11. The frames look cleaner if that makes sense. The program I am using smplayer has been tweaked the best way possible for movie watching. Been using the program for many years now it in honestly is the best program out there for video viewing in my opinion. VLC is the same and my wife thinks I'm crazy since she cannot see it but maybe my eyes are more sensitive to it.

I also know that the c7 doesn't support vvr but for some weird reason it helped and was noticable. Also fast sync has been helping together with vvr. Don't ask me why it is even when not supported(windows is a weird thing)

I had the deblur and dejudder off but will try turning it on and setting to 0 but even then it might make it worse because it is turning on a setting in a tv that uses more processing even if it is not doing anything.

It's been an issue for a bit that I have slowly improved but not completely removed over the years. Maybe it's my processor/gpu for 4k movies that may be the issue.
 
Thanks for trying to help here...

With movies running at 24p cannot gain frames naturally but it's really hard to explain unless you see it with your own eyes.

Things got better after getting pretty well everything removed from that I wanted from windows 11. The frames look cleaner if that makes sense. The program I am using smplayer has been tweaked the best way possible for movie watching. Been using the program for many years now it in honestly is the best program out there for video viewing in my opinion. VLC is the same and my wife thinks I'm crazy since she cannot see it but maybe my eyes are more sensitive to it.

I also know that the c7 doesn't support vvr but for some weird reason it helped and was noticable. Also fast sync has been helping together with vvr. Don't ask me why it is even when not supported(windows is a weird thing)

I had the deblur and dejudder off but will try turning it on and setting to 0 but even then it might make it worse because it is turning on a setting in a tv that uses more processing even if it is not doing anything.

It's been an issue for a bit that I have slowly improved but not completely removed over the years. Maybe it's my processor/gpu for 4k movies that may be the issue.
Found out what it was. I have always left system guard in NTLITE so I decided to try something new and remove it. It has completely stop the issue and is as smooth as butter.

I am extremely pleased that after all these years I finally got the silly bugger! I still cannot believe it. I tested over and over and same result. Anyone know why system guard may have done this?
 
System Guard is designed to protect UEFI & driver integrity, so it has to constantly check for tampering. Kernel drivers operate at the lowest system levels, so checks have to pass through many context switching layers. Which isn't cheap.

The common view is VBS kills gaming performance. Virtualization = good for security isolation, bad for performance (extra overhead even with dedicated CPU support)

Enterprise keeps tacking on virtualization layers (Device Guard, VBS, WDAG). Home/Pro don't default to these features since the consumer market is more sensitive to performance.
 
System Guard is designed to protect UEFI & driver integrity, so it has to constantly check for tampering. Kernel drivers operate at the lowest system levels, so checks have to pass through many context switching layers. Which isn't cheap.

The common view is VBS kills gaming performance. Virtualization = good for security isolation, bad for performance (extra overhead even with dedicated CPU support)

Enterprise keeps tacking on virtualization layers (Device Guard, VBS, WDAG). Home/Pro don't default to these features since the consumer market is more sensitive to performance.
After some more testing, my video player works the best it ever has. However now.my Netflix is the worse it ever has been. Win some and lose some with windows. Will keep this thread active as I figure things out.
 
Nice find and info guys, I'm certainly intrigued to learn more and tinker with this myself.

Being another virtualization feature, it sounds like if you disable virtualization related stuff in your bios, then Windows may not be able to use these features. Necrosaro, perhaps as a way to fix Netflix, you can leave System Guard intact via NTLite, but disable virtualization settings in the bios and see what happens?
 
Nice find and info guys, I'm certainly intrigued to learn more and tinker with this myself.

Being another virtualization feature, it sounds like if you disable virtualization related stuff in your bios, then Windows may not be able to use these features. Necrosaro, perhaps as a way to fix Netflix, you can leave System Guard intact via NTLite, but disable virtualization settings in the bios and see what happens?
Tried that too by going back with a system restore and unfortunately did the same thing
While you are in the bios look at disabling all sleep states etc.
My system is overclocked and all sleep states,eco and all that stuff I don't want have been disabled in the bios.
This is now reminding me of a couple episodes of Star Trek Voyager called "The year of hell part 1 and 2" If you don't watch star trek then you won't get it but it seems like one change can dramatically change other things in worse or better ways. Either way once I figure it out then I think I am all done with my system. Updates are blocked till late 2024 anyways so fingers crossed.
 
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