[Thread Superseded] G-Sync 101 w/Chart (WIP)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.
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jorimt
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Re: G-Sync 101 w/Chart (WIP)

Post by jorimt » 15 Jan 2017, 17:37

Bouttime wrote:what is strange is that with G-Sync on and V-Sync off the FPS goes down to 50-60 FPS and the game stutters badly like it would if my GPU couldn't handle the graphics settings. It's the only game that does this. I'll just leave V-sync on and be done with it.
Chalk it up to laptop specific G-Sync behavior. I know that G-Sync technology implemented in laptops is similar to the desktop implementation, but I have no doubt there are differences.

It looks like you got it resolved by enabling G-Sync + v-sync, which is (as has been covered) what was originally intended anyway. I don't have access to a G-Sync laptop, so I can't attest to the differences myself, but it would be interesting to know what they are, if any.
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Bouttime
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Re: G-Sync 101 w/Chart (WIP)

Post by Bouttime » 16 Jan 2017, 03:33

jorimt wrote:
Bouttime wrote:what is strange is that with G-Sync on and V-Sync off the FPS goes down to 50-60 FPS and the game stutters badly like it would if my GPU couldn't handle the graphics settings. It's the only game that does this. I'll just leave V-sync on and be done with it.
Chalk it up to laptop specific G-Sync behavior. I know that G-Sync technology implemented in laptops is similar to the desktop implementation, but I have no doubt there are differences.

It looks like you got it resolved by enabling G-Sync + v-sync, which is (as has been covered) what was originally intended anyway. I don't have access to a G-Sync laptop, so I can't attest to the differences myself, but it would be interesting to know what they are, if any.
I think the primary differences are caused by the combinations of monitor/screen refresh rates and their respective GPUs:

Desktop with a GTX 970 paired with a 1440 144hz monitor - Defaults to max prefered refresh rate as a game is unlikely to exceed 144 FPS therefore a cap is not required. Therefore I can also have V-Sync off.

Laptop with a GTX 970m paired with a 1080p 75hz screen - Defaults to let the 3D program control the refresh rate as a game is likely to exceed the 75 FPS and therefore a cap is required. Unfortunately it seems World of Tanks has trouble controlling the refresh rate/FPS and the FPS drop and the game stutters. Therefore I must have V-Sync on.

But again, congratulations on your post as this is possibly the most complete and comprehensive explanation on G-Sync/V-Sync I have seen.

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

Post by jorimt » 16 Jan 2017, 11:11

I'm fairly certain that no matter the (supported) GPU, at least with the desktop implementation, "Preferred refresh rate" defaults to "Highest available." As stated in my OP, it's to ensure your maximum refresh is utilized at all times, especially necessary for games that don't expose a refresh rate option. And I don't believe Nvidia is detecting the given power of the card, and dictating what that option should be set to, especially seeing as there really is no reason for the display to be set any lower than its native refresh rate with G-Sync enabled; G-Sync matches the refresh rate to the framerate after all.

As for the laptop implementation, again, either it differs from the desktop version, or that specific setting is glitched. I'd advise that you set it to "Highest available" on your laptop, if it isn't already.

Also, in reference to your comment of, "Therefore I can also have V-Sync off," you can, but you will still get tearing when there is a frametime spike, or when there is a sudden variance from one frame to the next. It doesn't just happen in the extreme upper or extreme lower range, it can happen anywhere between with G-Sync + v-sync off, thus the "link" icon w/connecting line in my chart between the two categories. I suppose I will have to make that a bit clearer.
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Author: Blur Busters "G-SYNC 101" Series

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

Post by Bouttime » 16 Jan 2017, 11:21

jorimt wrote:I'm fairly certain that no matter the (supported) GPU, at least with the desktop implementation, "Preferred refresh rate" defaults to "Highest available." As stated in my OP, it's to ensure your maximum refresh is utilized at all times, especially necessary for games that don't expose a refresh rate option. And I don't believe Nvidia is detecting the given power of the card, and dictating what that option should be set to, especially seeing as there really is no reason for the display to be set any lower than its native refresh rate with G-Sync enabled; G-Sync matches the refresh rate to the framerate after all.

As for the laptop implementation, again, either it differs from the desktop version, or that specific setting is glitched. I'd advise that you set it to "Highest available" on your laptop, if it isn't already.

Also, in reference to your comment of, "Therefore I can also have V-Sync off," you can, but you will still get tearing when there is a frametime spike, or when there is a sudden variance from one frame to the next. It doesn't just happen in the extreme upper or extreme lower range, it can happen anywhere between with G-Sync + v-sync off, thus the "link" icon w/connecting line in my chart between the two categories. I suppose I will have to make that a bit clearer.
To have the laptop set to 'highest possible' I'd have to use Nvidia Inspector as NCP doesn't show the option on the laptop, only the desktop.
Nvidia should revert back to having V-Sync on by default when G-Sync is on. For those wanting uncapped Framerates they can manually turn it off. Much simpler that way.

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

Post by jorimt » 16 Jan 2017, 15:16

If that option isn't in the official control panel on your laptop, I assume there is good reason, and thus you're probably fine at default settings.

As for "Vertical synchronization" being set to "On" at default, I agree.

Nvidia did have it like that for a short period multiple driver versions ago, but it created an issue where if you set it to anything other than "On," it would revert to "On" every system restart. I assume they made the change they did, because one, the aforementioned was being caused, and two, in 99% of instances, a game's built-in v-sync setting is identical to using the control panel's solution for G-Sync purposes.
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Re: G-Sync 101 w/Chart (WIP)

Post by Bouttime » 16 Jan 2017, 16:20

jorimt wrote:If that option isn't in the official control panel on your laptop, I assume there is good reason, and thus you're probably fine at default settings.

As for "Vertical synchronization" being set to "On" at default, I agree.

Nvidia did have it like that for a short period multiple driver versions ago, but it created an issue where if you set it to anything other than "On," it would revert to "On" every system restart. I assume they made the change they did, because one, the aforementioned was being caused, and two, in 99% of instances, a game's built-in v-sync setting is identical to using the control panel's solution for G-Sync purposes.
Yeah I remember when the settings were simpler. So are you saying in-game v-sync also only activates when outside the g-sync range? The same as NCP V-Sync?

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

Post by jorimt » 16 Jan 2017, 17:32

In-game v-sync, for all intents and purposes, is, in 99% of instances, the same thing as Nvidia control panel v-sync.

As I stated in my OP:
Nvidia Control Panel V-Sync vs. In-game V-Sync:
While Nvidia v-sync has no input latency advantage over in-game v-sync, and when used with G-Sync + fps limit, it should never engage, some in-game v-sync solutions may introduce strange frame pacing behaviors, enable triple buffer v-sync automatically (not optimal for the native double buffer of G-Sync), or simply not function at all. And as described in the "G-Sync Range" section, the G-Sync module relies on v-sync "On" to compensate for frametime variances and avoid tearing at all times. There are rare occasions, however, where v-sync will only function with the in-game solution enabled, and thus, if tearing or other anomalous behavior is observed with Nvidia v-sync (or visa-versa), user experimentation may be required.
I only recommend the control panel solution, because it rules out any in-game-specific performance quirks (which, again, are rare).

The "v-sync" in "G-Sync + v-sync on" isn't actually v-sync, either via the in-game or control panel option. G-Sync reverts to v-sync behavior above its range (as it can no longer adjust the refresh rate to the render rate), and within its range, it compensates for sudden frametime variances by suspending affected (not all) frames during the v-blank. With G-Sync + v-sync off, those same frames tear instead, as they are being displayed immediately, whether or not the previous frame has finished displaying.

G-Sync's goal is to display a single frame at a time as soon as it is rendered, as opposed to v-sync off (on a non-G-Sync display or otherwise), which shows every frame as soon as it is rendered, resulting in multiple frames being shown on the screen at once, thus the tearing.
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Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

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

Post by hammelgammler » 17 Jan 2017, 04:53

Well, I have a XB271HU, and the in-game fps limiter of Overwatch is totally out of control. I found out that I need to limit my fps to at least 155 with 165Hz Refreshrate. To really be sure I opted for 150 FPS. But now eveything is really smooth with no tearing, absolutely beautiful! :)

I do have V-Sync OFF and Triple Buffering OFF.

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

Post by jorimt » 17 Jan 2017, 10:40

hammelgammler wrote:Well, I have a XB271HU, and the in-game fps limiter of Overwatch is totally out of control. I found out that I need to limit my fps to at least 155 with 165Hz Refreshrate. To really be sure I opted for 150 FPS. But now eveything is really smooth with no tearing, absolutely beautiful! :)

I do have V-Sync OFF and Triple Buffering OFF.
Did you read my entire OP?

I'm wondering, because the main takeaway of my post, is that G-Sync + v-sync off is inferior to G-Sync + v-sync on in pretty much every way. With G-Sync + v-sync off, you're effectively getting adaptive sync. Not to be confused with Nvidia's "Adaptive V-Sync," adaptive sync is when the tear line of v-sync off is offset/phased to a less noticeable area of the screen (near the top or the bottom).

As I've already stated on this thread, tearing simply means there is more than one frame being shown on the display at once, and G-Sync's goal is to show a single frame at a time; G-Sync + v-sync off does not allow this in all instances, thus the partial tearing.

Inside the G-sync range (and with an appropriate fps limit), v-sync "On" has nothing to do with traditional v-sync, and it does not mean it is enabled. It's simply a poorly labeled toggle that allows G-Sync to compensate for sudden frametime variances that can cause tearing.

It's entirely your choice, but I'm just letting you know that with G-Sync + v-sync off + 150 fps limit, you're robbing yourself of 12-13 frames, and with no input latency advantage over G-Sync + v-sync on + fps limit. That, and it will tear (I known, I have the same display and game) at any point there is a frametime spike (asset loads, area transition, script trigger, load screen transition, etc) or sudden frametime variance from one frame to the next.

I recommend G-Sync + v-sync on (Nvidia control panel or in-game) + 162 fps limit.

I do appreciate the input, as it is evident by a couple of these post that I may need to make some of my OP points even clearer going forward.
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Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

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

Post by hammelgammler » 17 Jan 2017, 11:02

You are totally right, I'm sorry about my comment. It was a bit confusing with your other thread where you mentioned the 1ms G-Sync penalty and to cap the FPS even lower to not have tearing. There are also some charts which may be misleading, like the 120 FPS cap on 144Hz. I was a bit confused because of that, which Information is the correct one. :/

The one thing I wanted to mention that I do had the same experience, that you need to cap your FPS much lower with V-Sync OFF. I had noticably tearing with 162 FPS, and I'm pretty sure I felt more Input Lag as well in comparison to 150 FPS. All my testing is with Overwatch and the built in limiter.

But I find it interesting that in your newest charts from this thread, that V-Sync OFF is a tiny bit faster then ON (about 1ms). So isn't it technically a bit faster? I will try it out with V-Sync ON though and write my experience with it. :)

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