Blur Buster's G-SYNC 101 Series Discussion

[Chief Blur Buster]

Sorry if this has been answered. I have read the full article and I still have a few questions. With optimal settings are we talking 20ms compared to with everything shut off? Or is for example 15ms delay no matter what and gsync adds only 5ms extra? All this is hard for me to understand I wish there was a conclusion on what games you think its worth using on and games you think you shouldn't use it on.
I play mostly PUBG,OW,and Fortnite. Does having Gsync on but not capping frames add delay or is it basically doing nothing since i am not capping frames or using vsync in nvcp thats how i have been running it. I have the ASUS ROG Swift PG248Q I play at 144hz not at 180hz and even though i tried the optimal setting im just not sure any delay is worth it or not yet but i do admit it looks so smooth.

There are many causes of input lag in the entire chain.

The display is only one of them.

Here's a simplified diagram that demonstrates how lag can pile up:



Now let's limit scope to ONLY the display (plus drivers/GPU/API -- which has to work with the monitor to pull off variable refresh rate).

The sudden-lag-increase effect when framerates max-out
You should cap just below VRR maximum to reduce input lag. What happens is that input lag suddenly goes up as your framerate hits maximum. You've got a lag-change effect. This was first discovered in year 2014 with the GSYNC Preview #2 -- http://www.blurbusters.com/gsync/preview2 ... The solution to that is to cap your framerate slightly below GSYNC maximum, to prevent it. What happens is whenever your framerate suddenly hits maximum (e.g. 144fps), the input lag suddenly increases, until the framerate falls (e.g. 110fps), where the lag suddenly goes back to normal.

So to prevent the lag-increase effect of hitting your monitor's maximum Hz -- you cap your framerate a few frames per second below max, like 141fps at 144Hz. The 13 frames per second is a safety margin for the slight fluctuations in frame-capping accuracy.

Tests showed that in-game frame rate capping (e.g. CS:GO, Overwatch) had lower lag than external framerate cappers like RTSS or NVInspector. And that for external framerate cappers, RTSS had less input lag than NVInspector.

The common theme that we've found is that capping has less lag than not capping at all.
Generally speaking, roughly In order of laggiest to least laggy for "GSYNC + VSYNC ON" -- it went as follows:

[Biggest lag increase when framerates max out]
- No cap
- NVInspector cap
- RTSS cap
- In-game cap
[Smallest lag increase when framerates max out]

Capping better than no capping for GSYNC + VSYNC ON
So the moral of the story: If you're using variable refresh rate (with VSYNC ON at max) -- then cap your framerate below max Hz -- to prevent the lag-sudden-change effect.

Why cap a few frames per second below?
Cap a few frames per second below, in order to give enough breathing room -- because capping is not always perfect. For example, some frametimes might be 1/143sec and others 1/145sec -- the too-fast frametimes will start to pile up input lag if the display is not keeping up. Because caps are often imperfect, that small bit of safety margin helps. People cap a few frames per second below, e.g. 141fps at 144Hz GSYNC -- to allow maximal possible lag-reducing benefits.

This is essentially the "TL;DR" for whys of GSYNC frame rate capping.

[noobysnackz]

Thanks for the reply then why do none of the pros/streamers cap frames. I have used the gsync on,vsync on nvcp,ow in game cap 141, fortnite and pubg used rtss to cap 141 so if im going to use gsync on thats best correct. If i shut everything off zero ms delay?

[RealNC]

Thanks for the reply then why do none of the pros/streamers cap frames.

Because they don't know, or they don't use gsync.

have used the gsync on,vsync on nvcp,ow in game cap 141, fortnite and pubg used rtss to cap 141 so if im going to use gsync on thats best correct. If i shut everything off zero ms delay?

With gsync, 141FPS cap will give you the least amount of lag.

For PUBG, you can use the in-game limiter too. It's configured in a file. See:

https://pcgamingwiki.com/wiki/Playerunk ... frame_rate

I think Fortnite might also have an in-game limiter, but I don't know where.

[Chief Blur Buster]

Thanks for the reply then why do none of the pros/streamers cap frames. I have used the gsync on,vsync on nvcp,ow in game cap 141, fortnite and pubg used rtss to cap 141 so if im going to use gsync on thats best correct. If i shut everything off zero ms delay?

Capping is not necessary for VSYNC OFF which is what professional players use.

This type of capping only reduces lag only for GSYNC or FreeSync or other variable refresh-rate technology.

VSYNC OFF uncapped has the lowest possible input lag, but some players prefer to use GSYNC for PUBG.

The decision matrix is essentially:

Are you playing ultrahigh framerates, higher than refresh rates, for elite competitive gameplay? (e.g. CS:GO)
--> Use VSYNC OFF
--> Don't need a cap
--> See Advantages of Frame Rates Above Refresh Rates

Are you playing a game that usually have framerates below monitor max Hz and stutters like a mofo? (e.g. PUBG on 240Hz)
--> VRR (GSYNC) can improve aiming if the game is super-stuttery.
--> VRR (GSYNC) can benefit from having a cap, to avoid sudden lag in maxed-out framerate situations.
--> VSYNC OFF may still be preferred by professionals, but preference of GSYNC does certianly go up much more dramatically for games with framerates permanently below refresh rates & massive stuttering.

CS:GO is simply more popular than PUBG in eSports, and framerates in eSports are usually higher refresh rates, so VSYNC OFF begins to derive the (small) lag saving benefits from that. At the elite leagues, mere milliseconds can matter.

And due to the high framerates of CS:GO above refresh rates, is also why GSYNC is not often used in the CS:GO eSports competitions since CS:GO often runs at above 240 frames per second, and so GSYNC isn't as useful.

(However, frame-capped GSYNC has less lag than VSYNC ON or uncapped GSYNC, so GSYNC can be a solution to those people who really hate tearing, too -- professionals often put up with tearing to get the lowest theoretically possible lag).

[xenphor]

Why wouldn't Nvidia just have Gsync default to never maxing out the monitor's refresh rate then? It seems like there's no downside to never have it max out, and at the same time the benefit of not having the input lag spike.

[sharknice]

Thanks for the reply then why do none of the pros/streamers cap frames.

Because they don't know, or they don't use gsync.

have used the gsync on,vsync on nvcp,ow in game cap 141, fortnite and pubg used rtss to cap 141 so if im going to use gsync on thats best correct. If i shut everything off zero ms delay?

With gsync, 141FPS cap will give you the least amount of lag.

For PUBG, you can use the in-game limiter too. It's configured in a file. See:

https://pcgamingwiki.com/wiki/Playerunk ... frame_rate

I think Fortnite might also have an in-game limiter, but I don't know where.

Yep, all Unreal Engine 4 games do.

C:\Users\USERNAME\AppData\Local\FortniteGame\Saved\Config\WindowsClient\GameUserSettings.ini
FrameRateLimit=140.000000

[lexlazootin]

I think the main problem with pros and streamers not using it is because Nvidia never really advertised it correctly. It does so much more then 'prevent tearing at lower framerates' but that's all people thinks it does. I bet if you forced them to use G-Sync for a week a lot of them would stick with it.

It would be super nice if Nvidia did have a low latency fps cap built into the driver that can automatically cap games below the max refresh for G-Sync mode, it's so silly to have V-Sync kick in when they reach max because that's a big problem with a lot of people trying it for the first time is that they just get V-Synced and think it's shit.

[RealNC]

Why wouldn't Nvidia just have Gsync default to never maxing out the monitor's refresh rate then? It seems like there's no downside to never have it max out, and at the same time the benefit of not having the input lag spike.

Because people would then complain to nvidia "I bought a 144Hz gsync monitor but when I enable gsync I only get 142FPS, fix your shit nvidia!"

[RealNC]

Thanks for the reply then why do none of the pros/streamers cap frames. I have used the gsync on,vsync on nvcp,ow in game cap 141, fortnite and pubg used rtss to cap 141 so if im going to use gsync on thats best correct. If i shut everything off zero ms delay?

This type of capping only reduces lag only for GSYNC or FreeSync or other variable refresh-rate technology.

VSYNC OFF uncapped has the lowest possible input lag, but some players prefer to use GSYNC for PUBG.

We had this discussion before

This is not actually true. Capping the frame rate has latency benefits even with vsync off and gsync off, at least for GPU-bound games (like PUBG.) The latency reduction is significant in Overwatch (Jorim ran a test,) and that game tries to reduce latency as much as possible, even. In games that don't try to minimize latency, the latency reduction should be even more substantial.

My recommendation is to never run a game uncapped. Doesn't matter what game it is, always cap it. The benefit is consistency, and you're not increasing latency by doing so, because the increased frame latency of the lower frame rate is offset by the latency reduction of frame capping.

This is also true when using gsync on 240Hz monitors. Ideally, you shouldn't just set a 237FPS cap and call it a day. When the game falls below 237FPS, you get increased lag. You should monitor the game and find out what the framerate range is, and use a cap that the game will be able to actually hit most of the time. If that happens to be 170FPS for example, then you should use a 170FPS cap even on a 240Hz gsync monitor.

For CPU-bound games, the above is probably not true. But for GPU-bound games, it applies. This also means that if you can make a game CPU-bound (by lowering graphics settings), then you would probably eliminate the latency penalty of running uncapped. Although this remains to be actually tested.

For CS:GO, which is CPU-bound for most people (unless you run it on a potato GPU,) running uncapped is probably fine (but again, no one tested yet.) But for PUBG and OW, which are usually GPU-bound (unless you're running them on a beastly GPU and/or a lower resolution), capping your frame rate should give you a latency advantage regardless of whether you're using gsync or not.

In any event, testing this should be extremely interesting to people making money by competing in these games (or for people who aspire to be as competitive as possible even if they're not professionals.)

[Chief Blur Buster]

This is also true if the game has some latency side effects when uncapped. It has happened.

However, it doesn't have to, if the system has lots of spare threads (to do houskeeping stuff like drivers, like, you know, mouse, keyboard, even disk threads, etc), and the game does not inadvertently starve a process. Then why cap? (Rheoretical auestion).

Also, GSYNC 101 uncapped VSYNC OFF tests showed no lag disadvantage, but Jorim' system is also a high end multicore system.

So you and I are indeed both right in different angles -- it is simply a matter of circumstance.