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[Thread Superseded] G-Sync 101 w/Chart (WIP)

Talk about NVIDIA G-SYNC, a variable refresh rate (VRR) technology. G-SYNC eliminates stutters, tearing, and reduces input lag. List of G-SYNC Monitors.

Re: G-Sync 101 w/Chart (WIP)

Postby jorimt » 17 Apr 2017, 15:24

Chief Blur Buster wrote:Geek to geek, mentioning the case of 240Hz GSYNC -- and the need to cap below GSYNC limit...

...I successfully convinced the RTSS author to extend GUI frame limit to 300 in his next version. ;)

http://forums.guru3d.com/showthread.php ... ost5421412

Nice job!
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Re: G-Sync 101 w/Chart (WIP)

Postby sexpot » 18 Apr 2017, 15:35

So for those with 240Hz screens, what is the general consensus to frame limit? 238 fps?
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Re: G-Sync 101 w/Chart (WIP)

Postby RealNC » 18 Apr 2017, 16:00

sexpot wrote:So for those with 240Hz screens, what is the general consensus to frame limit? 238 fps?

Frame times get pretty tight at 240FPS, so as a safeguard I'd say 236FPS. Until someone is able to do a proper test, at least.
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Re: G-Sync 101 w/Chart (WIP)

Postby kurtextrem » 19 Apr 2017, 01:27

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Re: G-Sync 101 w/Chart (WIP)

Postby streetunder » 27 Apr 2017, 12:44

jorimt wrote:Nice job!


Hi, ive got a few questions for you, could you please help me,

Last month i purchased a new laptop, msi gt72vr 7re, it comes with TN 120hz 5ms with G-Sync, i always heard amazing things about g-sync:
- that it completely eliminates tearing, it smooths the low frame-rates and you dont need to use v-sync, and does not affect performance.

Ok, i so was like, when i get a new laptop i need one with g-sync, i hate tearing but i dont use v-sync because i get input lag, so g-sync is the solution.
The last days, ive been testing a few games, g-sync is turned on by default and v-sync is "controlled by the application", ok so far so good, i go to game options turn v-sync off, refresh rate of screen is set at 120hz.
Then i was surprised, i still get tearing in all games, so i went online to search for a solution or to find out if have a hardware problem, since i always heard that G-Sync doesnt need V-Sync to work...

Yesterday ive found out about this thread and read the 1st post, now everything is more "clear", so thank you very much for the information provided, you are helping lots of people. 8-)

A few questions:

1) If G-Sync is made to work with V-Sync, then why Nvidia never said anything about it?
The driver automatically puts g-sync on by default and v-sync "controlled by 3d application".
If G-Sync was made to work with V-Sync from the beginning, theres no advantage using G-Sync at all, because if [u]you turn V-Sync on, G-Sync will never work, and you will get V-sync inputlag. (it will work like a screen without G-sync basically)
So, you need to limit the frame-rate in a third party program, put 2 fps below max refresh rate, for everything to work at 100% and to get G-Sync to work right:
- This is a mess of technology, and badly designed, why is this not fixed yet by Nvidia? :evil:
G-Sync was released in 2013 or before, almost 4 years ago.

2) My screen is 120hz, so i need to limit the frame rate to 118fps for everything to work as it should?

3) If i have G-Sync on with V-Sync off, do i get any benefits from G-Sync?
I know i will get tearing but at low fps, G-Sync smooths the frame rate right?

4) In the screen options menu i see a 3D Option, does my screen supports 3D?

5) What happens if i turn G-Sync On with Adaptive Sync On?

6) Does G-Sync affects performance at all?
With G-Sync On, FireStrike 16.531
With G-Sync Off, FireStrike 17.682
-How is this possible?

Thank you very much for your time,

Cheers
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Re: G-Sync 101 w/Chart (WIP)

Postby jorimt » 27 Apr 2017, 13:35

streetunder wrote:Then i was surprised, i still get tearing in all games, so i went online to search for a solution or to find out if have a hardware problem, since i always heard that G-Sync doesnt need V-Sync to work...

Yesterday ive found out about this thread and read the 1st post, now everything is more "clear", so thank you very much for the information provided, you are helping lots of people. 8-)

I'm glad to hear you've found my information useful. And yes, the G-SYNC "v-sync on/off" settings has confused many. But the best way to put it, is that the setting has been poorly labeled; with G-SYNC enabled, v-sync never activates, regardless of the v-sync setting. The closest it gets, is when you exceed your refresh rate, at which point G-SYNC + v-sync on begins to behave like traditional v-sync as it can no longer adjust the refresh rate to the framerate.

My latest information on the G-SYNC v-sync on/off settings can be found here:
http://www.blurbusters.com/gsync/gsync101-range/

Much of my original post is outdated, and will become relatively irrelevant once my article is complete.

streetunder wrote:1) If G-Sync is made to work with V-Sync, then why Nvidia never said anything about it?
The driver automatically puts g-sync on by default and v-sync "controlled by 3d application".
If G-Sync was made to work with V-Sync from the beginning, theres no advantage using G-Sync at all, because if [u]you turn V-Sync on, G-Sync will never work, and you will get V-sync inputlag. (it will work like a screen without G-sync basically)
So, you need to limit the frame-rate in a third party program, put 2 fps below max refresh rate, for everything to work at 100% and to get G-Sync to work right:
- This is a mess of technology, and badly designed, why is this not fixed yet by Nvidia? :evil:
G-Sync was released in 2013 or before, almost 4 years ago.

There isn't an easy answer for this, as it's technically oriented and multi-faceted. First of all, when G-SYNC first released, there was no "v-sync" option. G-SYNC was simply an option alongside v-sync in the v-sync dropdown of the control panel. Later, due to popular demand, they exposed the G-SYNC "v-sync" option, so that when you exceeded your refresh rate, with G-SYNC + v-sync off, G-SYNC would deactivate, instead of reverting to v-sync behavior and adding input latency.

Since G-SYNC eliminates tearing and sync-induced input latency by adjusting the refresh rate to the framerate, it is limited by the max refresh rate of the display. G-SYNC was originally meant to be a replacement to v-sync, and made to be used within the refresh rate of the display. It also helps smooth framerate delivery, and is best used when you can't reach the max refresh rate in a given game, and you are experiencing a highly variable framerate.

If you're constantly exceeding 120 fps on your 120 Hz display, and by a significant amount in the majority of games you play (unlikely for max settings in the latest triple A games, for instance), you're better off playing with v-sync off on a high refresh rate monitor, if input latency is a prime concern. Also, the framerate limit is only necessary for games that exceed your refresh rate 99% of the time; if you're averaging 80 fps @144Hz, the framerate limit isn't needed. So it isn't G-SYNC that is "a mess of technology, and badly designed," but merely a limitation of the monitors G-SYNC is implemented on. The higher refresh rates on G-SYNC displays become, the more benefits of the technology you will see.

streetunder wrote:2) My screen is 120hz, so i need to limit the frame rate to 118fps for everything to work as it should?

I'm currently performing input latency re-test across all available refresh rates for my upcoming article, so I'll have way more details to share then. But yes, -2 fps under your refresh rate should be enough to prevent additional sync-induced input latency.

streetunder wrote:3) If i have G-Sync on with V-Sync off, do i get any benefits from G-Sync?
I know i will get tearing but at low fps, G-Sync smooths the frame rate right?

The benefit you'll get over G-SYNC + v-sync on is partial tearing, which means the next frame will be delivered slightly faster (sometimes) at the same framerate limit, usually in the bottom area of the screen.

I've only tested the desktop implementation of G-SYNC however, and I know that laptop implementation may differ. Battle(non)sense has a good video testing G-SYNC input latency on laptops here:
https://www.youtube.com/watch?v=ADYzuMe17q8

streetunder wrote:4) In the screen options menu i see a 3D Option, does my screen supports 3D?

I'm not an expert on 3D settings, so I don't know, maybe? Your monitor manual will probably tell you.

streetunder wrote:5) What happens if i turn G-Sync On with Adaptive Sync On?

Nothing, or nothing good. At best, it will simply act like G-SYNC + v-sync off.

streetunder wrote:6) Does G-Sync affects performance at all?
With G-Sync On, FireStrike 16.531
With G-Sync Off, FireStrike 17.682
-How is this possible?

For the latest G-SYNC modules with the latest hardware on desktop, no, there isn't a performance impact. I'm not sure about laptop. But the difference in score you're probably seeing there is 1, margin of error between tests, and 2, assuming you were using G-SYNC + v-sync on, G-SYNC limits the framerate to the max refresh of your display, whereas v-sync off (and G-SYNC disabled) allows your system to output frames above your refresh rate. Higher framerates = lower frametimes = better score. You should never benchmark with any syncing method or external framerate limit active.
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Re: G-Sync 101 w/Chart (WIP)

Postby RealNC » 27 Apr 2017, 23:29

G-Sync on laptops runs a shader on the GPU, since there is no hardware g-sync module. That shader does overdrive calculations, and possibly other, as-of-yet undisclosed work on the GPU. This can slightly decrease performance.

On Desktops, no shader is used. All calculations are done by the g-sync module.

But I don't think the performance difference would be as high as shown in your FireStrike bench though.
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Re: G-Sync 101 w/Chart (WIP)

Postby yanot » 07 May 2017, 02:18

Hello all,

Jorimt, I noticed that you set "Maximum pre-rendered frames" = 1 in your screenshot. Is this setting used when using G SYNC? IF yes, is it the recommended setting for G SYNC ?
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Re: G-Sync 101 w/Chart (WIP)

Postby Sparky » 07 May 2017, 03:21

yanot wrote:Hello all,

Jorimt, I noticed that you set "Maximum pre-rendered frames" = 1 in your screenshot. Is this setting used when using G SYNC? IF yes, is it the recommended setting for G SYNC ?

it is recommended, but it only matters in some situations. If you're using an in game framerate cap and you're never GPU limited, it shouldn't matter. It may or may not matter when you're using RTSS, I haven't tested that interaction.
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Re: G-Sync 101 w/Chart (WIP)

Postby kurtextrem » 07 May 2017, 03:34

The setting was discussed a few pages back, setting it to 1 introduces uneven frame times.
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