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.



869 Comments For “G-SYNC 101”

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kylmead
Member
kylmead

Hello sorry if this is a double post, I cant find my original. But basically im noticing fps drops and screen flickering when playing fortnite. My goal is to have the smoothest game and least input lag possible. Current running 237 capped fps and 240hz. Gsync on, vsync off, low latency mode off. Is there anything I’m missing for better performance/ smoothness?

NorfPews
Member
NorfPews

Hello. So I’ve been using the optimal guide for G-sync compatibility for most of my games (G-sync on, v-sync on, frame cap 141@144hz) but I’ve noticed that even a very small frame drop of 1 fps causes frame stutter which makes it noticeable in game. I was wondering if that is an intended thing of g-sync compatibility or if this is an issue because my monitor is technically not officially supported for gsync.

GrantVXR
Member
GrantVXR

Hi just wondered if you would be able to help me out. I have g sync enabled using your recommended settings and it works well with no noticeable tearing. I’m playing Call of Duty Warzone and my frames are fairly pinned at the 160fps ive set apart from some parts of the map it drops to 140fps. I’m after the lowest input latency possible so should I unable Nvidias low latency mode? If so which setting should I use? My gpu usage is 97/99%
Many thanks 🙂

shuaka
Member
shuaka

hey i’m using borderless windowed and am experiencing some weird interactions with the fps limiter(should i even fps cap in windowed/borderless?) i set the limit to 138 and game is stuttery but whne i set it to closest limit like 143 stutter is gone and with no cap it seems to run the same as with 143 hz cap but when in a fight scene the fps jumps over the desired 144hz.
1-do you need a fps cap in borderless windowed?
2-why does the game stutter when caping at lower than 143/142/141 the lower the worse it gets?
3-will it run as stuttery if my fps drops under 143 due to other circumstances and not the fps cap?

Moshercycle
Member
Moshercycle

If I have a 144hz monitor, get 109-141 (141 is my cap) fps in warzone, would it be better to have Vsync on or off? My average is roughly 120-130 fps from what I’ve noticed as I do not know how to properly find my average.

Also, would it be recommended to change my fps limit to ~120?

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