Blur Buster's G-SYNC 101 Series Discussion

[jorimt]

I'm not sure if this is the right thread since the discussion I want to bring up is from an article that links to this thread from years ago (https://blurbusters.com/gsync/gsync101- ... ttings/10/).

This is the official discussion thread for that article.

My understanding is that by enabling G-sync, it's possible to remove the DWM related additional input lag for windowed programs (which I think is caused by a forced vsync with DWM?), which on win 7 could be removed by disabling desktop composition.

From my original tests, it appears to be the case, yes. G-SYNC seems to change the flip mode of the compositor during borderless/windowed operation.

Does anyone know if as of now (i understand a few new versions of windows 10 have come out since that threat) the fix still works, as in it achieves the same input lag as you would see if you were to kill DWM, and
I was wondering if anyone knew if the same fix can be achieved with freesync.

For G-SYNC (and likely G-SYNC Compatible), as far as I know, yes. For FreeSync, I haven't tested it (and probably won't), so can't say for certain. Possibly.

[ecal]

You replied to a comment saying

For the absolute lowest input lag possible?
– G-SYNC off + V-SYNC off + an in-game FPS limit just under the highest possible framerate above the max refresh rate without maxing out the GPU (as to prevent an increase in the pre-rendered frames queue) + LLM on (this setting is only reducing input lag when your GPU is maxed, and you’re system is not limited by an FPS cap, FYI, and is only intended as a fallback in this configuration, or any other configuration).

My question is, why do you need to set an in-game FPS limit if by your testing at https://blurbusters.com/gsync/gsync101- ... ettings/9/ it shows best results when there is NO (0 fps) limit.

[RealNC]

My question is, why do you need to set an in-game FPS limit if by your testing at https://blurbusters.com/gsync/gsync101- ... ettings/9/ it shows best results when there is NO (0 fps) limit.

If you don't care about tearing, then no FPS limit is fine. The point is that if you use g-sync, it means you want to get rid of tearing. For that, you need to cap your FPS to something the monitor can display without tearing.

[jorimt]

My question is, why do you need to set an in-game FPS limit if by your testing at https://blurbusters.com/gsync/gsync101- ... ettings/9/ it shows best results when there is NO (0 fps) limit.

"V-SYNC OFF + 0 FPS Limit (2000 FPS+)" refers to CS:GO's "fps_max" parameter set to "0," at which point I got 2000+ FPS in an empty test map. In the actual game, I (along with the majority of other players) can't get anywhere near that.

As for setting an FPS limit, unless your system is GPU-limited at any given point (not an aspect that was covered in the article as it was not directly related to the article's primary subject; syncing methods), you don't need to set one with standalone V-SYNC off, you only need to set one when using syncing methods as to prevent sync-induced input lag (and, for G-SYNC, to keep it within its working range).

If you read the rest of the article in sequential order, it explains why.

[ecal]

Okay, got you. Thanks for clearing it up!

[jorimt]

Okay, got you. Thanks for clearing it up!

No problem.

[Imp07]

Hi there, I just purchased a LG UltraGear 27GL63T (27 Inch IPS 1080P 144hz GSync).

I noticed in most games with Gsync on, everything looks great. However certain games (Doom Eternal) in the menu or in certain sequences (gun mod training segments and even some spots staring off to the distance) I can get some pretty noticeable white screen flickering. This monitor has a few different game modes and switching to a mod with the "Faster" response time mitigates it but its still apparent.

Is this white flickering normal, especially in menus? Outer Worlds, Total War Warhammer 2, Gears Tactics, I have not noticed it but really with Doom eternal in the menu and other spots

[jorimt]

Hi there, I just purchased a LG UltraGear 27GL63T (27 Inch IPS 1080P 144hz GSync).

Looks like that's an official G-SYNC compatible FreeSync display, so you're set there.

I noticed in most games with Gsync on, everything looks great. However certain games (Doom Eternal) in the menu or in certain sequences (gun mod training segments and even some spots staring off to the distance) I can get some pretty noticeable white screen flickering. This monitor has a few different game modes and switching to a mod with the "Faster" response time mitigates it but its still apparent.

Is this white flickering normal, especially in menus? Outer Worlds, Total War Warhammer 2, Gears Tactics, I have not noticed it but really with Doom eternal in the menu and other spots

Could be game-specific, and may or may not be entirely G-SYNC related on your specific model. That is, it's probably because G-SYNC is enabled (you have verified this isn't happening in the game with G-SYNC off, right?), but may be caused by a combination of settings...

1. I noticed your display is HDR "capable," do you happen to have that mode active for Doom? If so, have you tried disabling it to see if it affects this?
2. Are you running G-SYNC in fullscreen or borderless/windowed mode via NVCP, and what window mode do you have that game set to?
3. Are you using the general recommended G-SYNC settings of G-SYNC on + V-SYNC on (NVCP or in-game for Doom) + minimum -3 FPS limit? Because I've seen occasional reports of flickering issues on G-SYNC compatible displays with G-SYNC on + V-SYNC off.

[hmukos]

But doesn't bottom tear imply that there is too much of a frametime variance? Consider 120fps fixed with RTSS at 144hz G-Sync monitor. In order for tearline to appear the last two scanouts should happen in 1-2ms less than 1/144 seconds. That means frametime of around 5 ms where perfect frametime should be 1/120=8.33ms. Isn't that too incosistent or have I misunderstood something?

It depends on what range the frametime variances are in. G-SYNC (on) + V-SYNC off will only tear when either A) they occur near the max refresh rate, due to some frames' render time exceeding the refresh rate (e.g. being "faster" than the delivery time of the display), or B) when a frametime spike abruptly occurs, which causes the system to not output a new frame for a frame or frames at a time.

With 120 FPS at 144Hz, so long as the latter doesn't occur (and you have a framerate limit in place to keep it at that average for the former), you won't see tearing with G-SYNC (on) + V-SYNC off, as the render time of a frame with an 120 FPS target (8.3ms per) is well within the display time of 144Hz (6.9ms), since G-SYNC will simply "pad" the VBLANK (the span between the previous and next frame) by 1.4ms (8.3ms - 6.9ms = 1.4ms; you can apply this to any frametime higher than the monitor's scanout rate), then deliver the (already rendered) frame in 6.9ms, repeat.

I won’t have access to my monitor for a couple of weeks. When I get to it I will try again and report here. Thank you for your help!

Sure, feel free to update here when you do.

Regarding the problem with tearing on G-Sync. I finally got access to my 144hz monitor. So the problem was that some games were tearing in G-Sync mode with 120fps cap (with V-SYNC OFF) even when RTSS showed perfectly flat line. Any clue what the problem could be?

Here's the video (tears start at about 8 sec into the video, and as you can see RTSS frametime graph is flat):
https://drive.google.com/file/d/12Nskhj ... sp=sharing

[jorimt]

Regarding the problem with tearing on G-Sync. I finally got access to my 144hz monitor. So the problem was that some games were tearing in G-Sync mode with 120fps cap (with V-SYNC OFF) even when RTSS showed perfectly flat line. Any clue what the problem could be?

Here's the video (tears start at about 8 sec into the video, and as you can see RTSS frametime graph is flat):
https://drive.google.com/file/d/12Nskhj ... sp=sharing

1) Your monitor model?
2) Your capture program must V-SYNC, because I'm not seeing any tearing in that video.