G-Sync/Fixed refresh rate per application

[PainkilleR]

Hey all!

I've been using a g-sync monitor for a long time, but I have never understood one thing about it. Hope somebody knows the answer.

So, let's assume G-Sync is enabled for full screen and windowed modes globally. Now, you can set a Monitor Technology to Fixed Refresh on per application basis in Program Settings tab (in NCP).

After setting Monitor Technology to Fixed Refresh rate, some apps will still run in g-sync mode normally, some apps will switch to fixed refresh rate mode, and some apps will stay in g-sync mode, but will behave as if they were running in fixed refresh rate mode.

The question is: what exactly dictates this behavior? Why some apps can be switched to fixed refresh rate mode while others not? Is it about an API, a fullscreen implementation or something else entirely?

[_I_]

in nvidia control panel, you can pick settings per game

[PainkilleR]

Originally posted by _I_:

in nvidia control panel, you can pick settings per game

That's not what I asked. I know you can set monitor technology on per game basis via nvidia control panel. The question is why this setting works for some apps and not for others.

[Supafly]

Originally posted by PainkilleR:

Originally posted by _I_:

in nvidia control panel, you can pick settings per game

That's not what I asked. I know you can set monitor technology on per game basis via nvidia control panel. The question is why this setting works for some apps and not for others.

Because it detects the games. If you want it to work for non games or games it doesn't detect add them.

Manage 3D Settings > Program Settings > Add

[PainkilleR]

Originally posted by Supafly:

Originally posted by PainkilleR:

That's not what I asked. I know you can set monitor technology on per game basis via nvidia control panel. The question is why this setting works for some apps and not for others.

Because it detects the games. If you want it to work for non games or games it doesn't detect add them.

Manage 3D Settings > Program Settings > Add

No. That's not the question either. :)

Let's say I wanted to set the Quake Remaster to a fixed refresh rate via ncp. If I do this when the game is using Vulkan, the setting would do nothing. After launching the game, the G-Sync will be still ON. However, if I set the game to d3d11, after launching the game G-Sync will be turned off.

All that said, I am not quite sure if a specific api is the requirement for that setting to work properly, as I am sure I have faced some d3d11 that wouldn't go into fixed refresh rate mode, if not set globally.

[Pocahawtness]

I think it is down to the game itself. Some games seem to behave, some don't. I switch on the fps display in steam so I can always keep an eye on the fps and look for visual defects to make sure the game is doing what i want it to do. If not, then I tweak the individual game settings in NCP. I have heard of some games that somehow manage to completely bypass NCP. I don't have a game like that myself so I can't say for sure that it's true.

[PainkilleR]

Originally posted by Pirate☠️Pocah:

I think it is down to the game itself. Some games seem to behave, some don't.

It is, but what exactly is the cause I am wondering.

At this point I have tried writing a few OpenGL fullscreen programs for the sake of experiment, and it seems like neither of them can interpret NCP's Monitor Technology setting properly (whether I am initializing the window in OpenGL by myself, or let GLFW/SDL2 do the job).

I guess it's down to an api after all. It seems like only directx programs can be affected by this setting. Other apis follow the global config settings.

So, unless I'll stumble upon the game that breaks that rule, the answer to that question the api used. I might be wrong though.

[Azza ☠]

Nvidia added a feature years ago to allow both G-SYNC and V-SYNC run together. The V-SYNC will cap the max FPS off, say if your monitor had 120Hz you can limit the max FPS to 120. That stops the graphics card from wasting time/heat/noise producing additional frames which the monitor will just discard anyways. When the FPS drops to like 93 FPS instead, the G-SYNC kicks in to take over, keeping it smooth and tear-free.

Is that what you are noticing with the fixed refresh rate?

[_I_]

old fast sync, would let the keep working at a higher fps than the output with vsync on

so if you could hit 120+fps on a 60hz display, it would only display the latest complete frames, instead of the first one, which would be about 8ms later


new vsync
display -> draw -> wait - repeat

old fast sync
draw -> dr_ -> display last complete draw -> aw -> draw - repeat

i forgot which one would figure out the draw time and wait before drawing
wait -> draw -> display - repeat

[PainkilleR]

Originally posted by Azza ☠:

Nvidia added a feature years ago to allow both G-SYNC and V-SYNC run together. The V-SYNC will cap the max FPS off, say if your monitor had 120Hz you can limit the max FPS to 120. That stops the graphics card from wasting time/heat/noise producing additional frames which the monitor will just discard anyways. When the FPS drops to like 93 FPS instead, the G-SYNC kicks in to take over, keeping it smooth and tear-free.

Is that what you are noticing with the fixed refresh rate?

Originally posted by _I_:

old fast sync, would let the keep working at a higher fps than the output with vsync on

so if you could hit 120+fps on a 60hz display, it would only display the latest complete frames, instead of the first one, which would be about 8ms later


new vsync
display -> draw -> wait - repeat

old fast sync
draw -> dr_ -> display last complete draw -> aw -> draw - repeat

That's all irrelevant to the topic.

[_I_]

it kinda of is, im not sure which method is used when gsync/freesync are enabled and fps is above max refresh rate

when its below, both will display the frame as soon as its complete

[Azza ☠]

Fixed Refresh adds blur and tearing if your refresh rate doesn't match your FPS, I don't use it.

Similar to ULMB (Ultra Low Motion Blur) supported by some monitors, you want FPS to match, otherwise should disable it and use G-SYNC instead if you have that available.

A real G-SYNC module builtin to the monitor is a much better option than either of those, unless it's only a G-SYNC compatible monitor which uses the cable to sync rather than a module.

Right-Click desktop > Nvidia Control Panel > Manage 3D Settings

I would recommend you click on "Restore" for the Global and Program Settings. Don't mess with those overwrites unless an app or game messes up with your default settings. It's actually better to use the Geforce Experience app which just adjusts the game settings, before even considering messing with those which overwrite both Windows and the Games settings.

[_I_]

fixed will add tearing with vsync off
stuttering with duplicated frames displayed when fps is below refresh rate
no blur at all

ulmb is backlight strobing, the display turning off backlight while pixels are changing colors between displaying different frames
thats often used on cheaper panels that cant change pixels fast enough to eliminate ghosting on their own