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Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 10:57
by jorimt
Just to preempt some questions on this:
https://www.nvidia.com/en-us/geforce/ne ... dy-driver/
NVIDIA Ultra Low Latency Mode Adds G-SYNC Support

Lower latency makes your games feel more responsive and snappy, and can give you an extra edge in multiplayer. To further reduce latency for our users, we introduced a new Ultra Low Latency Mode (NULL) in a recent driver that reduced graphics pipeline latency and accelerated response times.

Now, we’ve updated NULL to enable it to work in concert with G-SYNC and G-SYNC Compatible gaming monitors, for a superior tear-free, extra-responsive variable refresh rate experience, so you no longer need to choose between V-SYNC or low response times:

Image

The above chart shows how when VSYNC is ON, NULL is set to ULTRA, and G-SYNC is ON, end to end system latency is reduced by up to 20%. This means 20% faster reaction time from when you click the button on your mouse to when you see the result on your screen.

To enable NULL on a global or per-game basis, head to the NVIDIA Control Panel and navigate to 3D Settings > Low Latency Mode. Select On or Ultra, and click apply on the bottom right of the Control Panel.

To use NULL in concert with G-SYNC:
  • Enable Ultra Low Latency Mode
  • Scroll down to Vertical Sync and select On, either on a global or per game basis, and apply changes
  • Navigate to “Set up G-SYNC” on the left nav of the NVIDIA Control Panel
  • Enable G-SYNC and apply changes (note, if your monitor supports G-SYNC and ULMB, ensure “G-SYNC” is selected under the Monitor
  • Technology dropdown in Manage 3D settings)
  • In-game, disable V-SYNC, so the NVIDIA Control Panel can correctly apply your settings
In the past, gamers have had to choose between a tear free experience with VSYNC ON, and a lower latency experience with VSYNC OFF. With the release of our new Game Ready Driver, gamers now get the best of both worlds, ensuring they can enjoy a low latency, tear-free experience when gaming on G-SYNC and G-SYNC Compatible gaming monitors.
While it's great to see Nvidia appears to be making further allowances for G-SYNC when used in conjunction with Ultra-low latency mode, the fine print disclaimer in the above graph image should be noted:
* End to End (Mouse Click to Display Update) System Latency measured on GTX 1660 Super, R440.xx, X299, Rampage VI Apex, i9-900k 3.6GHz, 16GB Corsair DDr4, Win 10 19H1 x64, 4k @ 60hz at ~75FPS settings. Combined performance of Rainbow 6, Apex Legends, Fortnite, and Overwatch
This means the above results still apply best to GPU-bound situations (especially at lower refresh rates), and regarding G-SYNC + V-SYNC specifically in their tests here, it was with the framerate exceeding the refresh rate of the monitor (which means they were still getting sync-induced input lag, just a little less [about 1 and 1/2 frames @60Hz due to further reduction of the pre-rendered frames queue] with "Ultra").

Suffice to say, G-SYNC + V-SYNC + -3 FPS (minimum) limit is still going to be superior input lag-wise, at any refresh rate, and until more is learned/tested, if you're going to enable Low Latency Mode globally, my general recommendation is still to use "On" over "Ultra."

That said, as always, you should try both per game, and see what subjectively feels better regardless ("Ultra" simply has the possible risk of more stutter/slightly higher input lag in non-GPU-bound situations, likely due to the occasional skipped frame).

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 12:53
by Chief Blur Buster
This could reduce the latency differential between GSYNC below-Hz and equal-Hz framerates. Most people just don't bother to cap GSYNC 3fps below, so automating this by 75%+ with NULL will be a benefit to industry.

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 13:21
by jorimt
^ Yes, true, it's certainly better than not. I myself am going to enable "Ultra" globally for now, and (subjectively, non-scientifically) see how it reacts in a variety of games when compared to "On" (my usual setting).

It will also be interesting to see if any testing/re-testing is done soon on this by Battle(non)sense or the like.

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 15:00
by Vleeswolf
In some testing I did it seems that putting NULL to "Ultra" and Vsync to "On" automatically caps games to below the refresh rate of the monitor (97.3 FPS @ 100Hz gsync screen). With some monitoring using PresentMon, it also seems to have the same latency characteristics as previously capping to 97 FPS manually.

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 15:21
by Vleeswolf
Another observation: since the NVIDIA Ultra Low Latency (NULL) feature was added, the FPS limiter in NVIDIA's driver, set through NVIDIA Profile Inspector, is also low latency, that is, sub-frametime latencies measured by PresentMon, similar to RTSS. You only set the FPS limit and let the "Frame Rate Limiter Mode" to default. Previously, that caused additional latency due to the Rendering Queue filling up, but that's exactly what the NULL feature has eliminated. Now it's possible to have low latency in GPU limited scenarios, when hitting the monitor's refresh rate, and when setting a custom frame rate limiter, all using just the driver :-)

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 15:50
by jorimt
Hmm, in my short observation, at 144Hz with G-SYNC + V-SYNC + Ultra Low Latency + uncapped FPS, I am indeed getting an auto cap to 138 FPS in all of the three games I briefly tested.

Obviously, high-speed testing and the like will have to be done to say for certain, but if it functions like I think it does, and it is indeed auto capping below the refresh rate with G-SYNC active, then, theoretically, it could potentially have similar latency to using a -3 FPS limit with RTSS.

Again, it will be interesting to see if Battle(non)sense revisits in the near future.

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 15:57
by Vleeswolf
Tested some Vulkan games, e.g. Doom 2016, with VSYNC On (in-game off), NULL Ultra. There it does not seem to work and the game FPS hits the monitor refresh rate just like before, resulting in ~1 FPS of queuing latency.

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 16:01
by jorimt
^ That would make sense:
https://www.nvidia.com/en-us/geforce/ne ... dy-driver/
Our new Low Latency Mode is being released in beta with support for all GPUs in DX9 and DX11 games (in DX12 and Vulkan titles, the game decides when to queue the frame).

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 17:29
by jorimt
I forgot to mention, in addition to my previous comments, I have seen similar behavior in my testing with G-SYNC + Fast Sync:
https://www.blurbusters.com/gsync/gsync ... ettings/8/
Image

It also auto capped to 138 FPS @144Hz (as well as 97 FPS @100Hz, btw) and had similar input lag levels to G-SYNC + RTSS -3 FPS limit.

Re: Driver 441.08: Ultra-Low Latency Now with G-SYNC Support

Posted: 29 Oct 2019, 19:46
by Darktalon
Will this cost framerates to use? Like if I'm only getting 90 fps before with a 144 hz monitor, is it gonna cost some more frames to have ultra low latency running?