G-SYNC 101: G-SYNC vs. V-SYNC w/FPS Limit


So Close, Yet So Far Apart

On the subject of single, tear-free frame delivery, how does standalone double buffer V-SYNC compare to G-SYNC with the same framerate limit?

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

As the results show, but for 60Hz (remember, a “frame” of delay is relative to the refresh rate), the numbers are relatively close. So what’s so great about G-SYNC’s ability to adjust the refresh rate to the framerate, if the majority of added input latency with V-SYNC can be eliminated with a simple FPS limit? Well, as the title of this section hints, it’s not quite that cut and dry…

While it’s common knowledge that limiting the FPS below the refresh rate with V-SYNC prevents the over-queuing of frames, and thus majority of added input latency, it isn’t without its downsides.

Unlike G-SYNC, V-SYNC must attempt to time frame delivery to the fixed refresh rate of the display. If it misses a single one of these delivery windows below the maximum refresh rate, the current frame must repeat once until the next frame can be displayed, locking the framerate to half the refresh rate, causing stutter. If the framerate exceeds the maximum refresh rate, the display can’t keep up with frame output, as rendered frames over-queue in both buffers, and appearance of frames is delayed yet again, which is why an FPS limit is needed to prevent this in the first place.

When an FPS limit is set with V-SYNC, the times it can deliver frames per second is shrunk. If, for instance, the FPS limiter is set to 59 fps on a 60Hz display, instead of 60 frames being delivered per second, only 59 will be delivered, which means roughly every second a frame will repeat.

As the numbers show, while G-SYNC and V-SYNC averages are close over a period of frames, evident by the maximums, it eventually adds up, causing 1/2 to 1 frame of accumulative delay, as well as recurring stutter due to repeated frames. This is why it is recommended to set a V-SYNC FPS limit mere decimals below the refresh rate via external programs such as RTSS.

That said, an FPS limit is superior to no FPS limit with double buffer V-SYNC, so long as the framerate can be sustained above the refresh rate at all times. However, G-SYNC’s ability to adjust the refresh rate to the framerate eliminates this issue entirely, and, yet again, beats V-SYNC hands down.



662 Comments For “G-SYNC 101”

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BlackStorm82
Member
BlackStorm82

HI
“fixed refresh rate”
Do you have information about?

Is it correct that G-Sync does not work when I use this?
In-game [frame limit release mode]
When it comes to monitor technology G-Sync, 100-600 FPS was also released.

[fixed refresh rate]
When I activated the League of Legends with this function, 300FPS was fixed.

rocet
Member
rocet

Hi, maybe i’m misreading or misunderstanding the graphs/article but there is no downside to just using G-Sync ON + V-Sync OFF + No fps limit?

G-sync would activate when below 144fps and then ‘de-activate’ above 144? Causing no input lag?

Zehdah
Member
Zehdah

I know that for the lowest possible input lag, you want to find the highest framerate your system can achieve an average of 95-99% of the time without maxing your GPU usage and cap your framerate there with an in game limiter, but what do I do to achieve that in a game like Warzone where my FPS can be as low as 140 in big open areas or as high as 240 when inside a building or small area?

My CPU and GPU usage always seem to be very high at 85-97%. I have an i7 9700k and 1080ti, playing on a 240hz monitor. The game seems to be poorly optimized so I’m struggling to decide what to do.

fanatycme
Member
fanatycme

When I play DOTA 2, my fps is all the time at ~117 because i capped it, but at the end of the game, when match finishes the base gets destroyed and i get a FPS DROP from ~117 fps to 80-90 fps and my game STUTTERS, is it normal? i am playing with g sync, vsync and fps cap, i thought gsync is supposed to GET RID of stutter or I do SOMETHING WRONG?? during the rest of the game everything seems ok

i am using:
-nvcp: gsync on fullscreen, highest refresh rate, vsync let 3d app decide
-dota2: vsync on, fps max 117 (120hz monitor), highest video settings
-latest drivers, gtx 1070, monitor aw3418dw

AnonymousH
Member
AnonymousH

I typically prioritize input latency and thus normally run with G-SYNC but without any framerate limit or V-Sync, which causes some tearing at high framerates. I initially thought that Fast Sync eliminates tearing but introduces some microstutter, and that was all, making it a viable option in combination with G-SYNC, and the rest depends on preference (with G-SYNC: none = tearing, V-Sync + framerate limit = higher latency, Fast Sync = microstutter). However, if I’m reading this correctly, even G-SYNC + Fast Sync without a frame limit isn’t recommended because it limits the framerate to something lower than the monitor refresh rate, or runs starting at that slightly lower framerate?

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