G-SYNC 101: Control Panel


G-SYNC Module

The G-SYNC module is a small chip that replaces the display’s standard internal scaler, and contains enough onboard memory to hold and process a single frame at a time.

The module exploits the vertical blanking interval (the span between the previous and next frame scan) to manipulate the display’s internal timings; performing G2G (gray to gray) overdrive calculations to prevent ghosting, and synchronizing the display’s refresh rate to the GPU’s render rate to eliminate tearing, along with the delayed frame delivery and adjoining stutter caused by traditional syncing methods.

G-SYNC Demo

The below Blur Busters Test UFO motion test pattern uses motion interpolation techniques to simulate the seamless framerate transitions G-SYNC provides within the refresh rate, when directly compared to standalone V-SYNC.

G-SYNC Activation

“Enable for full screen mode” (exclusive fullscreen functionality only) will automatically engage when a supported display is connected to the GPU. If G-SYNC behavior is suspect or non-functioning, untick the “Enable G-SYNC, G-SYNC Compatible” box, apply, re-tick, and apply.

Blur Buster's G-SYNC 101: Control Panel

G-SYNC Windowed Mode

“Enable for windowed and full screen mode” allows G-SYNC support for windowed and borderless windowed mode. This option was introduced in a 2015 driver update, and by manipulating the DWM (Desktop Windows Manager) framebuffer, enables G-SYNC’s VRR (variable refresh rate) to synchronize to the focused window’s render rate; unfocused windows remain at the desktop’s fixed refresh rate until focused on.

G-SYNC only functions on one window at a time, and thus any unfocused window that contains moving content will appear to stutter or slow down, a reason why a variety of non-gaming applications (popular web browsers among them) include predefined Nvidia profiles that disable G-SYNC support.

Note: this setting may require a game or system restart after application; the “G-SYNC Indicator” (Nvidia Control Panel > Display > G-SYNC Indicator) can be enabled to verify it is working as intended.

G-SYNC Preferred Refresh Rate

“Highest available” automatically engages when G-SYNC is enabled, and overrides the in-game refresh rate selector (if present), defaulting to the highest supported refresh rate of the display. This is useful for games that don’t include a selector, and ensures the display’s native refresh rate is utilized.

“Application-controlled” adheres to the desktop’s current refresh rate, or defers control to games that contain a refresh rate selector.

Note: this setting only applies to games being run in exclusive fullscreen mode. For games being run in borderless or windowed mode, the desktop dictates the refresh rate.

G-SYNC & V-SYNC

G-SYNC (GPU Synchronization) works on the same principle as double buffer V-SYNC; buffer A begins to render frame A, and upon completion, scans it to the display. Meanwhile, as buffer A finishes scanning its first frame, buffer B begins to render frame B, and upon completion, scans it to the display, repeat.

The primary difference between G-SYNC and V-SYNC is the method in which rendered frames are synchronized. With V-SYNC, the GPU’s render rate is synchronized to the fixed refresh rate of the display. With G-SYNC, the display’s VRR (variable refresh rate) is synchronized to the GPU’s render rate.

Upon its release, G-SYNC’s ability to fall back on fixed refresh rate V-SYNC behavior when exceeding the maximum refresh rate of the display was built-in and non-optional. A 2015 driver update later exposed the option.

This update led to recurring confusion, creating a misconception that G-SYNC and V-SYNC are entirely separate options. However, with G-SYNC enabled, the “Vertical sync” option in the control panel no longer acts as V-SYNC, and actually dictates whether, one, the G-SYNC module compensates for frametime variances output by the system (which prevents tearing at all times. G-SYNC + V-SYNC “Off” disables this behavior; see G-SYNC 101: Range), and two, whether G-SYNC falls back on fixed refresh rate V-SYNC behavior; if V-SYNC is “On,” G-SYNC will revert to V-SYNC behavior above its range, if V-SYNC is “Off,” G-SYNC will disable above its range, and tearing will begin display wide.

Within its range, G-SYNC is the only syncing method active, no matter the V-SYNC “On” or “Off” setting.

Currently, when G-SYNC is enabled, the control panel’s “Vertical sync” entry is automatically engaged to “Use the 3D application setting,” which defers V-SYNC fallback behavior and frametime compensation control to the in-game V-SYNC option. This can be manually overridden by changing the “Vertical sync” entry in the control panel to “Off,” “On,” or “Fast.”



3071 Comments For “G-SYNC 101”

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DerConnor
Member
DerConnor

So what actually causes the tearing from “Upper & Lower Frametime Variances”? Is it because G-Sync is somehow unable to respond to a quick change in frametime (I read somewhere it uses a fixed polling frequency to update the current refresh rate)? And in the Valorant clips with the FPS capped to 142, shouldn’t this result in a constant frametime or is there some problem with how the FPS limiter works (introducing inconsistent frametimes)? I also can’t for the life of me see any tearing in the second Valorant clip.

Thanks a lot for this article, it was a super interesting and informative read.

Clueless
Member
Clueless

I read the article multiple times now and I feel like I didn’t understand anything.

I have a GSync compatible Display (LG 32GP850-B), set to 165Hz. GSync fullscreen is enabled. VSync ist set to on. FPS Limit is set to 162.

When I open the test on page 1 (G-SYNC Simulation of Variable Refresh Rate) and test Quebec or Stars for example the result on top (GSync) looks ok, the result at the bottom however (VSync on) does not. I see microstuttering and a blur here and there. But the moment I disable VSync at the simulation it looks ok again.

How does this behaviour in a windowed browser window (that sounds weird) fit your recommendation of GSync on + VSync on? Thank in advance.

HopperTron
Member
HopperTron

This is an amazingly detailed site and thanks for it!

I’m curious about advice here with respect to G-Sync + V-Sync + LLMU (or in-game framerate limiting) vs. advice I’ve read elsewhere — mainly for competitive shooters — around _not_ using G-Sync and instead running as high FPS as possible. The theory is that since input is calculated per frame, you get lower input lag with higher FPS at the expense of tearing, which kinda makes sense in the abstract. But what I’ve read in these articles suggests that slowing down the frames sent to the monitor via G-Sync does not necessarily affect input lag — possibly because internally the render loop is still calculating input, it’s just not showing up on the screen? So maybe what people think is lower latency is actually the ability to be aiming during a partial screen refresh?

I’d be curious as to your thoughts. Going from a 60Hz monitor to 144Hz has been absolutely amazing and good graphical fidelity is lovely but I mostly play online shooters, so if there is truly an advantage to forgoing image quality for very very high FPS then it might be worth making various profiles.

Bounty
Member
Bounty

Hello!

Is there a difference between Low Latency mode “On” and “Off”? Does it have any impact on Gsync at all?

HashiruOtoko
Member
HashiruOtoko

Any idea why my LG 27GL850 OSD shows Elden Ring in borderless windowed as running at 60Hz?

HashiruOtoko
Member
HashiruOtoko

Looks like it acts as more of an inaccurate FPS monitor, despite saying Hz, and that’s for both places in OSD that have a readout.

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