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.



1096 Comments For “G-SYNC 101”

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God Hands
Member
God Hands

Hi, jorimt! Thank you for creating this guide and still being active in its comments for all this time. I’m a fairly new PC owner and I have a couple of questions surrounding RTSS and a program called ISLC.

First question: I’m currently using my NVCP resolution that’s set to Ultra HD 4k native (NOT PC resolution 4k) because the LG CX TV and its HDMI 2.0 (UHD 48g).

The reason is because for some reason, the Ultra HD selection in NVCP allows RGB Full and doesn’t give me the ONLY option of YCBCR, which also doesn’t let me select Full dynamic range. I’m guessing because I’m choosing the “TV” resolution.

This is relevant because despite the UHD+ resolution looking better, more colorful and more crisp at the same resolution as the PC selection, the highest refresh rate availble is CAPPED at 60hz instead of the full 120hz I know the LG CX is capable of and can be selected in any PC resolution in the NVCP. (Side Note: what’s even stranger is that certain games seem to take advantage of the 120hz anyway despite my NVCP 60hz being selected from UHD resolution settings, meanwhile others are capped at 60.)

So my actual first question is this: since my NVCP resolution is selected as UHD AND 60hz despite being a 120hz monitor, do I set the RTSS to -3 under THAT refresh rate (which would become 57hz) or still set RTSS to 117hz for -3 because I’m using a 120hz 4ktv/monitor, despite the UHD resolution selection being 60hz in panel?

Secondly, what are your opinions on using something like ISLC or Timer Resolution(?) for decreasing input lag (and in ISLC’s case, input lag and memory) in conjunction with your G-Sync/V-Sync/RTSS instructions here? Necessary? Overkill? Incompatible? I don’t want too many cooks in the kitchen if it’s a problem. It claims to halve my 1ms response time to .5ms, but I’m not sure if there’s any hidden problems this could cause with your method that I should know about. Thank you! I admire your passion for optimal settings.

This is ISLC for reference. https://www.wagnardsoft.com/forums/viewtopic.php?f=18&t=1256&sid=ac940d134fc3d4ffe921578dc23dfb36

m_staf
Member
m_staf

Hello,

I have been having much trouble with my G-sync intermittently working for seemingly no rhyme or reason for months. I have followed all of the recommended steps for setting up Gysnc and have a Gsync certified monitor (Asus TUF VG27A). Gsync WILL work for a few of the games on my computer such as Red Dead Redemption 2 and Rise of the Tomb Raider. I can tell that it is working because of the Gsync enabled badge appearing in the game and a noticeable improvement in tearing. Gsync will not however work in games like Battlefield V or World of Warcraft classic (it previously did when I first built my computer). I figured this may be due to improper in game settings on my end at first. However, when using the Nvidia pendulum demo, I have not once been able to select the Gsync box in the demo. There are no signs of Gsync working at all in the demo and it is accompanied by terrible frame rate tearing. I can select the Vsync option in the demo (if that means anything).
I have done a clean reinstall of the drivers, tried multiple monitors, display port cables, HDMI cables, etc, default Nvidia control pannel settings. Nothing has seemed to work at all! It is incredibly frustrating as I have combed forums and boards for months looking for a solution. It is also upsetting spending the extra money for a certified Gsync monitor and still having the issues. I usually have a dual monitor setup. One monitor is a freesync Acer XF270HUA and the other is the Asus previously mentioned. I have tried testing one monitor at a time with the same issues so I do not believe it to be the fault of having dual monitors.

All settings on nvidia control panel are default besides the following

Set up G-SYNC > Enable G-SYNC, G-SYNC Compatible > Enable for full screen mode.
Manage 3D settings > Max Frame Rate 162 FPS
Manage 3D settings > Vertical sync >ON

Do you have any ideas of what could be causing the issue or inconsistency?

Thank you for your time and help!

drameloide
Member
drameloide

The results show a consistent difference between the three methods across most refresh rates (240Hz is nearly equalized in any scenario), with V-SYNC OFF (G-SYNC + V-SYNC “Off,” to a lesser degree) appearing to have a slight edge over G-SYNC + V-SYNC. Why? The answer is tearing…

about this paragraph, you said gsync + vsync off have tearing issues and this is completely wrong if you are in range of gsync, differences between vsync on + gsync and vsync off + gsync is only the plus of input lag vsync offer you

tbhee
Member
tbhee

For AMD is it correct to set the framerate limiter through Radeon Chill Min and Max = cap?

And for a game that does have an ingame limiter would it be overkill to be using that as well
as Chill?

Gsyncmasterace
Member
Gsyncmasterace

Hey there 😀

Do you guys know if there is any difference between gsync and a fixed refresh rate with an unlimited framerate ( lets say 400 fps at 240hz ).

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