Is Gsync (still) bad in Windowed Mode?

[Firefly]

Hey guys,

See this:


"Enable (only) for fullscreen mode" has been the default setting for Gsync for as long as I can remember.

In 2022, what downsides still remains for enabling Gsync in Windowed Mode that prompts Nvidia to have not flipped the default setting? There were discussions (some on this very forum) >4yrs ago where it was brought up that Windows didn't know how to handle Gsync properly yet, but that must have changed by now, no?

Also, does that setting affect the behavior/responsiveness of alt-tabbing out of exclusive-full-screen games?

Not a particularly important question - just curious.

[RealNC]

Windows knows about VRR now, but only when DWM is not active. That is, fullscreen mode. The windowed mode g-sync feature is still basically a hack. It kind of works, but produces stutter. The stutter seems to happen more often when a) the GPU load gets high, and b) when monitor refresh rate is not a multiple of the game's FPS. a seems to be more severe than b.

[Firefly]

Windows knows about VRR now, but only when DWM is not active. That is, fullscreen mode. The windowed mode g-sync feature is still basically a hack. It kind of works, but produces stutter. The stutter seems to happen more often when a) the GPU load gets high, and b) when monitor refresh rate is not a multiple of the game's FPS. a seems to be more severe than b.

Thanks! Follow-up:

1) What does VRR and DWM stand for?

2) Does the setting affect alt-tabbing in & out of fullscreen games? I don't play games in windowed mode anyways, but I do alt-tab.

[RealNC]

1) What does VRR and DWM stand for?

VRR is Variable Refresh Rate. NVidia's VRR product name is g-sync, AMD's is freesync.

DWM is the Desktop Window Manager of Windows. It composes the image you see on the screen by copying the contents of windows and then mixing them all together and applying various effects on top of it (like shadows, blur effects, etc) and then presents the end result. When it is active and doing all those things (compositing, effects, whatever), g-sync cannot work. The reason is very technical, but let's just say that DWM simply gets in the way between the game and the nvidia driver. When the nvidia driver doesn't have direct access to the game's graphics because DWM sits between it and the game, g-sync stops working. Windowed g-sync mode is a hack that modifies the way DWM works in order to get g-sync to work, but it's not reliable. Fullscreen mode, where DWM is disabled, and the GPU driver has direct access to the game, is much better.

2) Does the setting affect alt-tabbing in & out of fullscreen games? I don't play games in windowed mode anyways, but I do alt-tab.

As far as I can tell, the setting only affects windowed mode games. (Including "bordeless" mode, which is just windowed mode where the window is maximized, and the window borders hidden.)

[Firefly]

Thanks @RealNC , that clears it all.

[Gabe777]

Hello people.

May I ask: if G sync is not working "perfectly" with borderless wibdiws, and guven DirectX 12 games only use borderless at best, will g sync EVER work flawlessly with DirextX 12 games ?

DirectX 12 games will eventually become the norm given that AFAIK, it is required for ray tracing, so it doesn't bode well.

I am having difficulties with Metro Exodus Extended which enforces DirectX 12.

[jorimt]

May I ask: if G sync is not working "perfectly" with borderless wibdiws, and guven DirectX 12 games only use borderless at best, will g sync EVER work flawlessly with DirextX 12 games ?

DX12's fullscreen mode is not the same as traditional borderless/windowed; it's a newer flip model (similar to fullscreen optimizations) that acts like exclusive fullscreen when the game window is focused, but allows DWM composition when it is unfocused, such as during alt+tabs or when an external overlay is triggered.

This is the reason G-SYNC still engages in DX12 with only "Enable for full screen mode" instead of "Enable for windowed and full screen mode" applied in the NVCP, since the DX12 fullscreen flip model still counts as exclusive fullscreen.