Adjustable LFC point for G-sync enabled Freesync?

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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seregost
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Joined: 02 Dec 2019, 13:23

Adjustable LFC point for G-sync enabled Freesync?

Post by seregost » 02 Dec 2019, 13:37

Can the starting frequency of LFC be controlled in G-sync for a freesync monitor via CRU? I have a monitor with a freesync range of 48-144hz, but the nvidia driver seems to be kicking into LFC at 60hz instead of 48hz.

This is really annoying because there is a noticable brightness change when it happens on my VA panel. In many games the menu is capped at around 60 fps so the rapid oscillation between LFC and back results in a flickering effect.

I would be happy if I could just adjust the LFC range either down OR up slightly because then I could just cap games at 60fps and be fine. However when I adjust the freesync range in CRU it has no effect.

Monitor: AOC CQ27G1
GPU: RTX 2070

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Re: Adjustable LFC point for G-sync enabled Freesync?

Post by Chief Blur Buster » 02 Dec 2019, 20:13

seregost wrote:
02 Dec 2019, 13:37
Can the starting frequency of LFC be controlled in G-sync for a freesync monitor via CRU? I have a monitor with a freesync range of 48-144hz, but the nvidia driver seems to be kicking into LFC at 60hz instead of 48hz.

This is really annoying because there is a noticable brightness change when it happens on my VA panel. In many games the menu is capped at around 60 fps so the rapid oscillation between LFC and back results in a flickering effect.

I would be happy if I could just adjust the LFC range either down OR up slightly because then I could just cap games at 60fps and be fine. However when I adjust the freesync range in CRU it has no effect.

Monitor: AOC CQ27G1
GPU: RTX 2070
Are you seeing the monitor FPS meter (refresh cycle counter) in your monitor rapidly leap between 60fps and 120fps? Then you’re right.

Are you seeing the FPS meter (refresh cycle counter) in your monitor jump to 60fps? Then the game menus are running at 30 frames per second and LFC is doubling them up to 60 frames per second.

On my games, most game menus are running at 30 frames per second, which causes the FPS counter in my monitor to leap to 60fps — indicating LFC x 2 being activated. Movies at 24 frames per second sometimes creates an LFC x 3 (72fps instead of 48fps), depending on what the bottom-end of VRR range is currently.

ToastyX is capable of modifying the FreeSync range on an AMD Radeon card. But it doesn’t seem to affect the LFC range of an NVIDIA graphics subsystem, and it doesn’t change the 30fps frame rate of some in-game menus (depends on the game).

You can also measure the frame rate of your in-game menu using the in-game framerate counter and/or use RTSS as the frame rate. For any given consistent frame rate — divide the monitor’s frame rate measurement (if monitor has built-in FPS counter), by the computer’s frame rate measurement (game or RTSS framerate measurement), and you’ll see an integer ratio. 1 means LFC not active, 2 and above means LFC is currently active.
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       • List of Ultrawide Monitors

seregost
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Joined: 02 Dec 2019, 13:23

Re: Adjustable LFC point for G-sync enabled Freesync?

Post by seregost » 02 Dec 2019, 21:18

Thanks for the swift response!

To answer your question, yes I am seeing the frame-rate in the monitor's OSD bounce back and forth between integer ratio 1 and 2 of the in-game framerate. See the screenshot below as an example. Green is the frame-rate reported by the nvidia overlay, and red/orange is the monitor's reported frame-rate.

In this case I had RTSS cap my frame-rate at 61 fps. Per the nvidia overlay the in-menu frame rate on several of the games I play (ex. Overwatch, RDR2, Starcraft 2) is capped at around 60 fps. But I see the fps in the monitor oscillating back and forth between 60 fps and 120 (ish) FPS, indicating to me that LFC is cycling on and off at 60 hz.

The effect is that there is a sort of flickering in brightness because (I assume) the intrinsic brightness of the monitor is slightly different at 60hz vs 120hz. I expected that behavior at 48 hz, but it doesn't seem like G-sync is using the configured freesync range.
LFC
LFC
LFC.jpg (697.78 KiB) Viewed 1373 times

Alex130130
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Joined: 24 Nov 2019, 21:21

Re: Adjustable LFC point for G-sync enabled Freesync?

Post by Alex130130 » 07 Dec 2019, 14:04

I have similar issue with ASUS VG248QG G-sync compatible monitor. My osd hz counter jumps around. I’ve tried everything. Here’s video: https://youtu.be/1IUwJAquMYQ

seregost
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Joined: 02 Dec 2019, 13:23

Re: Adjustable LFC point for G-sync enabled Freesync?

Post by seregost » 07 Dec 2019, 14:49

I am not 100% sure, but it seems to be slightly different because your frame-rate isn't getting cut in half like it would if LFC was enabled.

I'm relatively new to this, but I think some variance in frame-rate on the OSD is probably normal. I figure that's probably just due to frame-time variance that isn't apparent with the in-game fps monitor? I get that in almost all games, even if they have really high stable frame rates and LFC doesn't engage.

Do you notice large changes in brightness when it happens?

Also, have you checked what your frame-time looks like in something like MSI Afterburner?

Alex130130
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Joined: 24 Nov 2019, 21:21

Re: Adjustable LFC point for G-sync enabled Freesync?

Post by Alex130130 » 08 Dec 2019, 13:53

Picture is ok. No flickering or pulsing, brightness is ok. Frame rate of a game is stable in all fps counters: RTSS, Steam’s fps counter and Fraps when i use fps cap. Frame times aren’t perfect though. And the main thing is with G-sync on, fps drops get more noticeable than when it’s off, especially when i move my cursor. I think it’s just cons of G-sync. But in some games my osd hz counter is in sync with fps: in Borderlands 3 with dx12 and Fortnite in dx12 mode. With dx12 it works much better.

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