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.



273 Comments For “G-SYNC 101”

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Phroster
Member
Phroster

Why is it, that in most games, borderless fullscreen + gsync, gives worse results then exclusive full screen mode? (uneven frametimes, micro stutters)
Using a frame limiter to set the framerate -3 below the refresh rate makes it even worse when using borderless fullscreen.

I did find that G-sync + Fast sync + borderless fullscreen seems to give better results in some games. Still limiting the frame rate in borderless fullscreen, introduces microstutters.

Why is borderless fullscreen so unreliable with gsync enabled?

jdawg
Member
jdawg

Hey, so I didn’t know about turning on V-sync in NVCP only, but before I did that I was getting the occasional stutter even though the action on screen wasn’t that intense. I have RTSS showing a graph of FPS and I notice there are several little dips happening every second. The game moves smooth but then I get the stutter occasionally. I’ve closed everything unnecessary but maybe there’s more to close…not sure what other processes I can close in Windows 10 and I haven’t done any optimizations like in Windows 7.

Fast forward to setting it up as recommended here (141 FPS limit in game for my 144Hz monitor, G-sync on, V-sync ON in NVCP only, V-sync OFF in-game) and I noticed that the dips on the graph are even deeper…however I haven’t seen a stutter yet and the game plays very smooth with no lag. Any explanation for those dips in the graph though?

metalpizza123
Member
metalpizza123

Hi hi, Just a quick heads up for users with several displays of varying refresh rates. Windows will sometimes only report the lowest refresh rate monitor as the system-wide V-Sync target. After testing on driver ver 436.02, with 3 different monitors, here are my findings. I testeed with 3 games, all had similar behaviour. I used the recommended settings as per the guide.
NVCP V-sync ON
Gsync Enabled
Ingame FPS Limiter or RTSS used
Ingame Vsync/buffering disabled

Main monitor :G-Sync, 144hz.
Second Monitor 60 Hz
In game Framerate 60~

Main monitor :G-Sync, 144hz
Second monitor 75 Hz
In game Framerate 75~

Main monitor G-sync,144hz
Second monitor, 60hz
third monitor, 75hz
In game framerate 60~

Only main monitor: G-Sync 144hz
In game frame rate 140~

There’s probably a way to disable this, but for now I’ve resorted to just unplugging my other monitors. Just a note for any multi monitor users. I wish I could test more, but I just wanna play games.

kucki
Member
kucki

Should we use the “Low Latency Mode” On or Ultra with G-Sync?

Chief Blur Buster
Admin

Possibly beneficial for uncapped GSYNC + VSYNC ON. Will need to be tested.

This will reduce lag differential of below-Hz (GSYNC behavior) versus match-Hz (VSYNC ON behavior).

Creakffm
Member
Creakffm

Hello Guys, really Intresting Article/Guide but i wanna know something from you.

i Playing Games since 20 Years i know in Old Times with 60 HZ Monitors i play Competitive Games with VSYNC off to get most FPS ingame.

So back to 2019.

Im Using a Nvidia Geforce 1080 TI and my Monitor is 240 HZ DELL Alienware AW2518HF with GSYNC on Displayport Cable.

i wanna Optimizing all to Play Competitive. Actual i play with Ingame Fortnite Framerate Limit 240 HZ because see this by a lot of People.

When i wanna get less Inputlag i set in Nvidia Inspector Framerate Limiter to 245,244 ( more FPS than HZ or less and than which one is best? )

thanks for Answering

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