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.



1655 Comments For “G-SYNC 101”

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Linkaran
Member
Linkaran

It’s a great article, I understood a lot of things

However, recently the Mass Effect Legendary Edition game was released, it imposes different framerate limitation ranges like 30/60/120/144 and 240.

This makes it impossible to limit the FPS to 117 for a 120hz screen for example via the nvidia control panel
Cannot disable this option in the game, forced to play 30/60/120/144 or 240 fps or nothing

What do you recommend in this case?

Enable 120 FPS limitation in Mass Effect + Vsync game with nvidia control panel?

or the limit of 120 FPS in the game + vsync in the game?

this game is a special case that I find interesting concerning the GSYNC + VSYNC because it forces its framerate limitation in the game

askobilv
Member
askobilv

A lower fps limit would rob frames

What if I want to reduce load on my GPU and CPU by capping to lower values like somewhere between 60-90 (on 144hz monitor)

Could that work or I will experience bad implications?

Jimmy
Member
Jimmy

Hi, thank you for the great articles you guys are amazing.
I have one quick question. I’ve recently bought a G-SYNC monitor 144hz and its capable of 180hz OC. The game that I play gives me around 160-170 fps. Do you recommend capping my fps @ 141 or OC the monitor and let the G-SYNC do its job while capping @ 177 ? My main goal is lower input lag with the highest fps.

18koko
Member
18koko

Hi I just want to ask if I enable low latency mode in nvidia control panel and also enble ingame low latency mode (valorant nvidia reflex on+boost) will it conflict with each another? Do I enable both or no?

christofin
Member
christofin

Hello, thank you for the wonderful article. I’ve been using a g-sync compatible monitor for a long time and have always left g-sync on, vsync on, and a framerate cap in the Nvidia control panel at 156fps with a 160hz monitor.

I think as time has gone on I’ve become more sensitive to noticing microstuttering in games. For example PUBG is an absolute stutterfest and it’s something I used to not notice. Likewise with games with awful frame pacing issues in general like Dark Souls 3. I’ve always tried to stick to games that have very smooth frametimes, like Overwatch. But even now with the reflex patch, I’ve seen a few frametime spikes here and there in Overwatch and I have to admit that it does bother me.

My question to you is this: is there something I can do system wide to reduce frame time spikes? Would turning off vsync help? I saw in the article in the stuttering section, you mentioned that if the game has a pause, no settings can fix that, but are there any settings that could mitigate how noticeable it is?

I used to try to just throw money at the hardware to mitigate stuttering. I’ve upgraded my ram and power supply, for example. Right now I have a 9900k with a mild overclock and a 3090 founders edition running at stock. I do aggressively monitor what tasks I let run in the background and I generally keep software closed while I’m playing games. Is there anything else I can do to help reduce stuttering in various games?

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