G-SYNC 101: G-SYNC Fullscreen vs. Borderless/Windowed


DWM Woes?

Requested by swarna in the Blur Busters Forums, is a scenario that investigates the effects of the DWM (Desktop Windows Manager, “Aero” in Windows 7) on G-SYNC in borderless and windowed mode.

Unlike exclusive fullscreen, which bypasses the DWM composition entirely, borderless and windowed mode rely on the DWM, which, due to its framebuffer, adds 1 frame of delay. The DWM can’t be disabled in Windows 10, and uses it’s own form of triple buffer V-SYNC (very similar to Fast Sync) that overrides all standard syncing solutions when borderless or windowed mode are in use.

To make sure this was the case, all combinations of NVCP and in-game V-SYNC, as well as the Windows 10 “Game Mode” and “fullscreen optimization” settings were tested to see if DWM could be disabled, and tearing could be introduced; it could not be, so Game Mode and fullscreen optimizations were disabled once again, and NVCP V-SYNC was re-enabled across scenarios for consistency’s sake.

The question is, does DWM add 1 frame of delay with G-SYNC using borderless and windowed mode?

Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings

Overwatch, shows that, no, with G-SYNC enabled, both borderless and windowed mode do not add 1 frame of delay over exclusive fullscreen. Standalone “V-SYNC,” however, does show the expected 1 frame of delay.

CS:GO was also tested for corroboration, and ought to have the same results, as DWM behavior is at the OS-level and should remain unchanged, regardless of the game…

Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings

Sure enough, again, G-SYNC sees no added delay, and V-SYNC sees the expected 1 frame of delay.

Further testing may be required, but it appears on the latest public build of Windows 10 with out-of-the-box settings (with or without “Game Mode”), G-SYNC somehow bypasses the 1 frame of delay added by the DWM. That said, I still don’t suggest borderless or windowed mode over exclusive fullscreen due to the 3-5% decrease in performance, but if these findings are true across configurations, it great news for games that only offer a borderless windowed option, or for multitaskers with secondary monitors.



46 Comments For “G-SYNC 101”

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pervyjutsu
Member
pervyjutsu

Should “Reduce Buffering” option in Overwatch be enabled or disabled? Many competitive/pro players suggest having reduce buffering on to get higher framerate and reduced input lag but would having this option on have a negative effect on G-SYNC?

Also I recently upgraded my system to a i7-8700k and 1080ti. I usually sit at a steady 300fps on Overwatch now and use a 240hz monitor (Asus PG258Q). Would G-SYNC be worth using in this case?

vityapapa
Member
vityapapa

The Csgo input-lagg is the best g-sync off+v-sync off and fps_max 0?
i have 144hz monitor.

bcbuse
Member
bcbuse

First, this is the best Gsync/Vsync information on the internet. I appreciate the effort you put into this, well done.

I read a comment you posted somewhere that ‘technically’ the absolute least input lag would be with Gsync Off + Vsync Off + Framerate upcapped(getting at least 2x the monitor refresh rate). Can you approximate how much less input lag that would be versus Gsync On + Vsync On(NVCP) + Framerate capped 2 below monitor refresh rate?

vityapapa
Member
vityapapa

Hi,
on the 9th pages of the CSGo test, V-sync off+288fps limit
the G-sync was turn on or turn off?
thnx

Epicbeardman
Member
Epicbeardman
Thanks for this excellent guide. I now know that the most optimal configuration for my 60hz G-Sync monitor is G-Sync ON + V-Sync ON (NVCP) + V-Sync OFF (in-game) + 57 FPS limit. However, there are some games which utilize V-Sync but don’t provide an option to disable it, either in-game or via an external config file. As stated in section 14 of the guide: “…some in-game V-SYNC solutions may introduce their own frame buffer or frame pacing behaviors, enable triple buffer V-SYNC automatically (not optimal for the native double buffer of G-SYNC)…” In this scenario, should I still use… Read more »
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