Does VSync being enabled both in NVCP and in-game 'stack' or 'clash'?

[D-Crypt]

I have VSync enabled globally in NVCP and VSync off in 99% of games. I've also capped the max frame rate to below my refresh rate to ensure that I'm within G-Sync range at all times.

The only application that I require VSync to enabled with is RetroArch. RA requires VSync to be on within the program itself to ensure that "Sync to Exact Content Frame Rate" works (i.e. G-Sync for emulated games). I use NVCP's profile settings to change Nvidia's VSync setting to "Use the 3D application setting" in this instance.

Out of curiosity, would having VSync on in both NVCP and the application cause both VSync processes to run simultaneously, effectively adding input lag with zero benefit? Or does NVCP override/cause some changes in VSync behaviour that is best avoided by using profile settings to ensure only one VSync method is used at any given time?

[RealNC]

No. Vsync is a single flag that is being set on the rendering pipeline. If it's not set by the game, it can be set by the driver. However, there can be differences between the two. For example vsync ON in-game and ON or OFF in nvcp can mean triple-buffered vsync, if that's what the game wants. Vsync OFF in-game and ON in nvcp can mean double-buffer vsync.

But anyway. The point is that having both in-game and nvcp vsync won't somehow result in some "twice as strong vsync" or anything, as there's no such thing

[jorimt]

Like @RealNC said, the V-SYNC "option" is basically a flag set at the driver level when used with G-SYNC, so both the in-game and NVCP V-SYNC option will activate that flag once. It can't be activated twice.

The only reason you typically don't want to "stack" the NVCP V-SYNC option with an in-game V-SYNC option is A) it's redundant, and B) the in-game solution may activate more than the G-SYNC-related flag at the driver and/or engine-level that the NVCP option will not (be that triple buffer behavior, render queue related buffering changes, etc).

That said, 99% of the time, it's fine whether you use the NVCP or in-game V-SYNC option in combo with G-SYNC, and if there's a scenario in which you're "stacking" both V-SYNC options, it's not ideal, but it isn't the end of the world either, at least in the majority of cases.

Just avoid it when you can and stick with one solution.

[D-Crypt]

Very concise and helpful replies, thanks to you both!