NVIDIA Low Latency Mode - On or Off for less Input lag?

Everything about latency. Tips, testing methods, mouse lag, display lag, game engine lag, network lag, whole input lag chain, VSYNC OFF vs VSYNC ON, and more! Input Lag Articles on Blur Busters.
User avatar
jorimt
Posts: 1296
Joined: 04 Nov 2016, 10:44
Location: USA

Re: NVIDIA Low Latency Mode - On or Off for less Input lag?

Post by jorimt » 15 Aug 2020, 11:17

Defox wrote:
15 Aug 2020, 10:46
There was one more question.
To get lower input latency in "Low Latency Mode = Ultra" - we need to limit in-game FPS below 138 (in the case of a 144 Hz monitor).
But. If there is no in-game limiter. Does it make sense to limit FPS using the nvidia control panel (as we know it increase input lag)? Will this decrease the input lag or, on the contrary, increase it?
Ultra's auto FPS limiter uses the same solution Nvidia's "Max Frame Rate" option uses, which is typically on par with the RTSS limiter in frametime performance and input lag. So if there's no in-game limiter and you don't want to use RTSS to limit the FPS below the Ultra auto-limiter (in cases you need a lower than 138 FPS limit to prevent max GPU usage), switch LLM to "On," and set the Nvidia "Max Frame Rate" option to the desired limit instead.

Again, with G-SYNC, the only known difference between LLM "On" and "Ultra," is that Ultra sets an auto FPS limit in supported games. Beyond that, they both reduce the pre-rendered frames queue in GPU-bound situations the same way via an MPRF value of "1" (with G-SYNC).

- G-SYNC + V-SYNC + LLM Ultra = MPRF "1" + auto FPS limit
- G-SYNC + V-SYNC + LLM On = MPRF "1"
(jorimt: /jor-uhm-tee/)
Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

Defox
Posts: 11
Joined: 16 Jul 2020, 11:59

Re: NVIDIA Low Latency Mode - On or Off for less Input lag?

Post by Defox » 15 Oct 2020, 06:34

jorimt wrote:
01 Aug 2020, 09:35
Basically, if you use G-SYNC, it's safe to leave LLM set to "On."
In a recent video of Battle(non)sense about "NVIDIA Reflex", I noticed that it recommends setting the low latency mode to "Off". Why not "On"? If I am correctly aware, then the "On" value forces the maximum number of prepared frames to 1, which will give us confidence that the game will not prepare more than 1 frame.

Are there any explanations and assumptions why he recommends installing it "Off"?

User avatar
jorimt
Posts: 1296
Joined: 04 Nov 2016, 10:44
Location: USA

Re: NVIDIA Low Latency Mode - On or Off for less Input lag?

Post by jorimt » 15 Oct 2020, 09:22

Defox wrote:
15 Oct 2020, 06:34
In a recent video of Battle(non)sense about "NVIDIA Reflex", I noticed that it recommends setting the low latency mode to "Off". Why not "On"? If I am correctly aware, then the "On" value forces the maximum number of prepared frames to 1, which will give us confidence that the game will not prepare more than 1 frame.

Are there any explanations and assumptions why he recommends installing it "Off"?
Because Reflex effectively removes the pre-rendered frames queue entirely, thus LLM has nothing to reduce. Reflex is an LLM replacement.

That said, you can leave LLM "On" globally for games that don't support Reflex, as Reflex will ignore LLM settings anyway.
(jorimt: /jor-uhm-tee/)
Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

Defox
Posts: 11
Joined: 16 Jul 2020, 11:59

Re: NVIDIA Low Latency Mode - On or Off for less Input lag?

Post by Defox » 17 Oct 2020, 10:39

jorimt wrote:
15 Oct 2020, 09:22

Because Reflex effectively removes the pre-rendered frames queue entirely, thus LLM has nothing to reduce. Reflex is an LLM replacement.

That said, you can leave LLM "On" globally for games that don't support Reflex, as Reflex will ignore LLM settings anyway.
However, in earlier videos, when the NVIDIA Reflex did not yet exist, he still conducted tests with the LLM turned off. It seems to me in this way he misleads his audience a little (since they will just repeat after him without knowing what exactly this setting does), since some games may be configured to prepare more than 1 pre-frame, which will eventually cause additional input lag.

User avatar
jorimt
Posts: 1296
Joined: 04 Nov 2016, 10:44
Location: USA

Re: NVIDIA Low Latency Mode - On or Off for less Input lag?

Post by jorimt » 17 Oct 2020, 14:26

Defox wrote:
17 Oct 2020, 10:39
since some games may be configured to prepare more than 1 pre-frame, which will eventually cause additional input lag.
In GPU-bound scenarios, yes, in non-GPU-bound scenarios, almost never. That and LLM only works in some games. It doesn't work in DX12 or Vulkan at all, for instance.

LLM honestly isn't a very impactful setting when compared to other input lag reduction methods.
(jorimt: /jor-uhm-tee/)
Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

Post Reply