DLSS 3 and V-Sync

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Custerly
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DLSS 3 and V-Sync

Post by Custerly » 10 May 2024, 13:37

Is the consensus still to disable v-sync when running DLSS 3? I have seen a lot of contradictory discourse around this and am looking for the definitive blur busters (tm) verdict here.

daemonjax
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Re: DLSS 3 and V-Sync

Post by daemonjax » 13 May 2024, 09:10

You can force enable vsync in the control panel while using FG.

You'll want to also enable ultra low latency, though.

That's how I play cyberpunk 2077 (overdrive+dlss_quality+dldsr_2.25x+fg+whatever else I forgot). Runs perfectly. I don't have a gsync LCD panel, though, so that might complicate things for people who do. I dunno.

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RealNC
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Re: DLSS 3 and V-Sync

Post by RealNC » 13 May 2024, 10:41

daemonjax wrote:
13 May 2024, 09:10
You'll want to also enable ultra low latency, though.
It doesn't matter, because DLSS FG has Reflex as a hard requirement. So ULL doesn't have any effect.
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Custerly
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Re: DLSS 3 and V-Sync

Post by Custerly » 14 May 2024, 08:48

RealNC wrote:
13 May 2024, 10:41
daemonjax wrote:
13 May 2024, 09:10
You'll want to also enable ultra low latency, though.
It doesn't matter, because DLSS FG has Reflex as a hard requirement. So ULL doesn't have any effect.
So am I correct in understanding that the options are:
A) screen tearing (no v-sync)
B) extra 200ms or so latency (due to v-sync issue with DLSS 3)

??

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Re: DLSS 3 and V-Sync

Post by RealNC » 14 May 2024, 13:29

Custerly wrote:
14 May 2024, 08:48
So am I correct in understanding that the options are:
A) screen tearing (no v-sync)
B) extra 200ms or so latency (due to v-sync issue with DLSS 3)

??
Not sure what you mean. There is no vsync issue with DLSS 3. I use g-sync with an FPS cap below max refresh rate to prevent vsync lag. In other words, I do the exact same thing as when playing games without DLSS 3.
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Re: DLSS 3 and V-Sync

Post by Custerly » 14 May 2024, 15:38

RealNC wrote:
14 May 2024, 13:29
Custerly wrote:
14 May 2024, 08:48
So am I correct in understanding that the options are:
A) screen tearing (no v-sync)
B) extra 200ms or so latency (due to v-sync issue with DLSS 3)

??
Not sure what you mean. There is no vsync issue with DLSS 3. I use g-sync with an FPS cap below max refresh rate to prevent vsync lag. In other words, I do the exact same thing as when playing games without DLSS 3.
So you run without any v-sync? Screen tearing can still occur below max refresh rate, so you have no screen-tearing mitigation?

I'm also surprised to hear you say you operate as normal with screen caps while using DLSS 3. The discourse on this site seems to suggest that causes an interpolation issue with DLSS 3 and you want to either let Reflex cap the frames or use a cap at half of the desired output framerate, when supported (as in Cyberpunk).

What am I misunderstanding?

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RealNC
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Re: DLSS 3 and V-Sync

Post by RealNC » 14 May 2024, 16:11

Custerly wrote:
14 May 2024, 15:38
So you run without any v-sync? Screen tearing can still occur below max refresh rate, so you have no screen-tearing mitigation?
I do use vsync. As I said, I do the same thing as without DLSS 3. G-sync + vsync + cap.
I'm also surprised to hear you say you operate as normal with screen caps while using DLSS 3. The discourse on this site seems to suggest that causes an interpolation issue with DLSS 3 and you want to either let Reflex cap the frames or use a cap at half of the desired output framerate, when supported (as in Cyberpunk).

What am I misunderstanding?
When using an FPS cap with DLSS 3, it's Reflex that does the capping. This happens automatically if you cap in NVCP. With RTSS, you need to change the limiter from "async" to "Nvidia Reflex" in the RTSS settings. Only the Reflex limiter (it's in the driver) can cap DLSS 3. With the Reflex limiter, you cap directly to your target FPS. Not to half.

PS:
If your RTSS version is too old, then it doesn't have Reflex limiter support. Make sure you're using a recent version.
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Re: DLSS 3 and V-Sync

Post by Custerly » 14 May 2024, 19:51

RealNC wrote:
14 May 2024, 16:11
Custerly wrote:
14 May 2024, 15:38
So you run without any v-sync? Screen tearing can still occur below max refresh rate, so you have no screen-tearing mitigation?
I do use vsync. As I said, I do the same thing as without DLSS 3. G-sync + vsync + cap.
I'm also surprised to hear you say you operate as normal with screen caps while using DLSS 3. The discourse on this site seems to suggest that causes an interpolation issue with DLSS 3 and you want to either let Reflex cap the frames or use a cap at half of the desired output framerate, when supported (as in Cyberpunk).

What am I misunderstanding?
When using an FPS cap with DLSS 3, it's Reflex that does the capping. This happens automatically if you cap in NVCP. With RTSS, you need to change the limiter from "async" to "Nvidia Reflex" in the RTSS settings. Only the Reflex limiter (it's in the driver) can cap DLSS 3. With the Reflex limiter, you cap directly to your target FPS. Not to half.

PS:
If your RTSS version is too old, then it doesn't have Reflex limiter support. Make sure you're using a recent version.
Wow, thanks for dropping all of this knowledge on me. So, if I am understanding correctly...

I have a 165 hz display. I typically run G-Sync + V-Sync ("on" in NVCP) + RTSS limiter at 162 when pushing max frames. When I enable DLSS 3 and Reflex in a game, I continue to run G-Sync + V-Sync ("on" in NVCP), and I either ensure RTSS is set to Reflex limiter and cap to 162 that way, or I disable RTSS cap and instead cap via NVCP "Max Frame Rate" setting at 162. Is that right?

Should I also use an in-game cap 3 FPS below the NVCP/RTSS(with Reflex limiter) cap as described in the "best practices" post I linked above?

Also, what about cases like Cyberpunk where there's that interpolation issue? Do I then cap to 81 (half of desired output frame rate)?

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Re: DLSS 3 and V-Sync

Post by RealNC » 15 May 2024, 05:33

Custerly wrote:
14 May 2024, 19:51
I have a 165 hz display. I typically run G-Sync + V-Sync ("on" in NVCP) + RTSS limiter at 162 when pushing max frames. When I enable DLSS 3 and Reflex in a game, I continue to run G-Sync + V-Sync ("on" in NVCP), and I either ensure RTSS is set to Reflex limiter and cap to 162 that way, or I disable RTSS cap and instead cap via NVCP "Max Frame Rate" setting at 162. Is that right?
Yeah. But note that Reflex behaves like ULL. That is, if vsync is enabled, it's gonna cap to something like 156FPS or so (forgot the exact value.) So you don't actually need to manually cap, unless you want something lower than that.
Should I also use an in-game cap 3 FPS below the NVCP/RTSS(with Reflex limiter) cap as described in the "best practices" post I linked above?
As I mentioned above, this happens automatically by Reflex when using vsync (and it's gonna be more than just 3FPS.)
Also, what about cases like Cyberpunk where there's that interpolation issue? Do I then cap to 81 (half of desired output frame rate)?
I don't have that game installed right now, but are you sure there's an issue? Reflex limiter should work just fine as-is, AFAIK.
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Custerly
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Re: DLSS 3 and V-Sync

Post by Custerly » 15 May 2024, 09:30

Should I also use an in-game cap 3 FPS below the NVCP/RTSS(with Reflex limiter) cap as described in the "best practices" post I linked above?
As I mentioned above, this happens automatically by Reflex when using vsync (and it's gonna be more than just 3FPS.)
Thanks for clarifying this. So, I suppose there's really no reason to implement a manual cap since DLSS 3 will ensure I am not CPU limited if I cannot meet the automatic cap implemented by Reflex + V-Sync, and in that case I'd be GPU limited which doesn't seem to cause frametime spikes. Do you agree with that?
Also, what about cases like Cyberpunk where there's that interpolation issue? Do I then cap to 81 (half of desired output frame rate)?
I don't have that game installed right now, but are you sure there's an issue? Reflex limiter should work just fine as-is, AFAIK.
I also don't have it installed, but I've read on this site (in the link I posted above) and elsewhere that there is an issue with that game and perhaps a small handful of other games that necessitates the half-cap approach. I don't have personal experience with that though.

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