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.



3388 Comments For “G-SYNC 101”

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TeeNam
Member
TeeNam

for competitive games like valorant, say for example the xg2431 monitor, would the g sync optimizations here be better than using strobing?
if the question still have some missing info for clarification, please ask me further.

epicjjoey
Member
epicjjoey

Can I use V-Sync in game or does it have to be in the nvcp?

xcheeezz
Member
xcheeezz

Hello! Is there any research on how a 2nd monitor with activated gsync influences latency?
Does disabling gsync for the 2nd display (which only shows youtube, discord, spotify etc.) result in lower/higher game latency? Or is this completely irrelevant?

Pessut
Member
Pessut

Hello! I have a monitor with 8ms pixel response time. If i enable NVIDIA Reflex will it also lower pixel response time making me see LESS motion blur when i move my mouse around in First Person Shooter for example?

JeritoBurrito
Member
JeritoBurrito

Appreciate the write up and sorry if this has been asked a million times. If I’m using an FPS limiter 3 below refresh rate should I still use in game reflex?

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