Framerate Cap, g/sync and brightness flickering (Odyssey G7)

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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PedroPortnoy
Posts: 7
Joined: 23 Apr 2021, 07:56

Framerate Cap, g/sync and brightness flickering (Odyssey G7)

Post by PedroPortnoy » 23 Apr 2021, 11:27

Hello, everyone!

First of all I'd like to thank all the members of this forum for all the tips I'v been able to take advantage of in the past.

I've recently purchased a Samsung Odyssey G7 27'' monitor and have been playing mostly Assassin's Creed Unity whithout noticing any of the famous brightness flickering associated with this monitor. I recently started playing another game (AC Chronicles: China) and started noting some severe flickering in the intro animations, and very faint flickering during gameplay.

After that I went back to AC Unity to search for it and actually noticed a tiny bit of flickering in some situations, but very hard to tell.

I've been playing AC Unity with NCP framerate cap set to 65 FPS (because some cosmetic physics are tied to Framerate in this game, like other AC games) with g-sync on and v-sync off, with no tearing and smooth gameplay, despite the eventual flickering.

I understand Brighness Flickering while using g-sync is due to monitors beiing brighter at higher refresh rates and that's why this monitor flickers a lot when the Framerate fluctuates around the lower limit of VRR range. Thanks to the information section on the OSD, i was able to confirm that the LFC was kicking in at anything lower than 90 FPS using nVidia Pendulum Demo and that, in fact, when going over and below that would cause visible flickering. Checking refresh rate during AC Unity gameplay confirmed it was around 130 Hz (2*65), but fluctuating from around 100 to 160 and it wouldńt go out of LFC.

I was able to change the VRR range to 50-240 (instead of 90-240) using CRU and tested it on Pendulum and it worked perfectly with no flickering. I even tried setting the pendulum interval to 65-65 to see if there was any fluctuation on the refresh rate, but it was a rock solid 64-65 Hz, no flickering whatsoever. I then tried AC Unity and still noticed the same faint flickering in some situations; when checking the OSD on the monitor, it woud go pretty fast from around 50 to 80 Hz, whick I suppose is the reason why there is flickering.

The next step was installing RTSS and checking if frametimes were unstable due to the Framerate cap: they were not. They were unbelievably stable actually, both in the AC games and in Pendulum and using either NCP framerate cap or RTSS framerate cap.

What I was able to notice is that the refresh rate on the OSD of my G7 would fluctuate a lot less in heavy scenes (like open space with a lot of NPC's, where it would stay within 62-68) compared to indoor scenes (50-80). It seems the lower the GPU load, the more instable the refresh rate of the monitor and the more flickering is noticeble.

So, after all that, I have some questions:

1- Why does the Refresh Rate of the monitor fluctuates in games with framerate cap but not in the pendulum demo locked to 65?

2- Is this due to Fullscreen Optimizations? (I disabled it but I'm not sure it actually makes the game run in Exclusive Fullscreen)

3- What can I do to be able to use framerate cap wthout flickering?

Important: if I run games uncapped, there is no refresh rate fluctuation or flickering at all, it just happens when capping framerates.

My specs:

CPU: i7 8700K @ 5.0 Ghz
GPU: ZOTAC RTX 3080 AMPHOLO

Thank you in advance

Vleeswolf
Posts: 36
Joined: 25 Aug 2017, 15:59

Re: Framerate Cap, g/sync and brightness flickering (Odyssey G7)

Post by Vleeswolf » 24 Apr 2021, 06:29

It could still be flickering because Low-Framerate Compensation (LFC) kicks in for slow frames. If you are seeing an average of 65 FPS, there can still be frames that are too slow. Try checking the 0.1% FPS to see if this could be the issue.

The best solution is to run those games at a 60 Hz refresh rate. It will prevent LFC and brightness flickering. Hopefully your monitor will still be able to do VRR at that refresh rate, but it may be that you don't even need it.

PedroPortnoy
Posts: 7
Joined: 23 Apr 2021, 07:56

Re: Framerate Cap, g/sync and brightness flickering (Odyssey G7)

Post by PedroPortnoy » 24 Apr 2021, 07:57

Vleeswolf wrote:
24 Apr 2021, 06:29
It could still be flickering because Low-Framerate Compensation (LFC) kicks in for slow frames. If you are seeing an average of 65 FPS, there can still be frames that are too slow. Try checking the 0.1% FPS to see if this could be the issue.

The best solution is to run those games at a 60 Hz refresh rate. It will prevent LFC and brightness flickering. Hopefully your monitor will still be able to do VRR at that refresh rate, but it may be that you don't even need it.
Thank you for your reply

That doesn't seem to be the issue, however. I did check the 0.1% FPS after you suggested it, still not getting into LFC. After that, I actually tried other ways to play at locked 60 FPS (Fastsync, NCP vsync, ingame vsync, turning off adaptive sync, etc) and no Vsync method seem to work for some reason: while in loading screens and menus it works (showing 240/120/80/60/48 FPS) but as soon as the game is loaded, framerate is uncapped (I suppose it would be normal for fastsync, but not other methods). Very odd. I will try reinstalling the drivers and restore the monitor to default settings and try one thing at a time.

Thanks again

PedroPortnoy
Posts: 7
Joined: 23 Apr 2021, 07:56

Re: Framerate Cap, g/sync and brightness flickering (Odyssey G7)

Post by PedroPortnoy » 28 May 2021, 19:31

I really hope these findings might help anyone who owns this monitor and wants to use it's VRR feature without Flickering or Stuttering (setting VRR control in the monitor OSD eliminates flickering but introduces stuttering):

After playing around with games that would hit different framerates, I was able to identify the specifics refresh rate values that caused flickering: it hapeens whenever the refresh rate goes above/below these values: 80 Hz, 104 Hz and 200 Hz. Basically, it flickers 40 Hz below the officially supportes refresh rates: 120 Hz, 144 Hz and 240 Hz.

So basically, if your refresh rate doesn't cross these values (80/104/200), there is no flickering (at least I can't see any).

I thought I could just set a framerate cap with RTSS to something like 100 Hz or 190 Hz (depending on the game) and keep my refresh rate to 240. Unfortunatly, if the framerate cap kicks in, I get flickering because the refresh rate spikes randomly (I can see it happening on the monitor OSD) often to 200+, even though frametimes are absolutely steady and the monitor is syncing perfectly. It gets worse with lower GPU % loads. These spikes don't happen when the framerate stays below the framerate cap, though, with the refresh rate being really stable and equal to the framerate, as it should be.

One thing that ACTUALLY works really well to prevent the flickering is to set a custom resolution with something like 195 Hz framerate. This way, if I set the framerate cap to 100 Hz or 190 Hz, although the refresh rate still spikes according to the OSD, it can't go over 200 Hz, so there is no flickering. This is easily done in NVCP for the native reolution and below.

But here is my problem: in some games, I want to use nVidia DSR (Dynamic Super Resolution) and it doesn't let me set the refresh rate to anything different to 60/120/144/240 ingame, so I can't use the above to prevent flickering. Is there any way to actually get a custom refresh rate to be used with DSR?

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