Blur Buster's G-SYNC 101 Series Discussion

[Noisyjam]

hey can i use Nvidia control panel to limit FPS or should i use rtss. would there be any negatives if i use the frame limiter thats in Nvidia control panel.

[jorimt]

hey can i use Nvidia control panel to limit FPS or should i use rtss. would there be any negatives if i use the frame limiter thats in Nvidia control panel.

This was answered in the article:
https://blurbusters.com/gsync/gsync101- ... ttings/11/

*As of Nvidia driver version 441.87, Nvidia has made an official framerate limiting method available in the NVCP; labeled “Max Frame Rate,” it is a CPU-level FPS limiter, and as such, is comparable to the RTSS framerate limiter in both frametime performance and added delay.

[Jeroenmfb]

Hi everyone,

I'm having an issue with my monitor and NVIDIA driver. I have G-SYNC enabled + VSYNC (only in nvcp) and the monitor runs at 390Hz. However, when I turn on Reflex + Boost to further lower latency and cap FPS below the monitor refresh rate, it locks my FPS to 351 instead of something close but below 390 FPS.

Has anyone else experienced this or have any suggestions on how to fix it?

Thanks in advance for your help!

PS: I don't know if this is the correct place to post or if I should have posted this under the XV252QF thread

[RealNC]

Hi everyone,

I'm having an issue with my monitor and NVIDIA driver. I have G-SYNC enabled + VSYNC (only in nvcp) and the monitor runs at 390Hz. However, when I turn on Reflex + Boost to further lower latency and cap FPS below the monitor refresh rate, it locks my FPS to 351 instead of something close but below 390 FPS.

Has anyone else experienced this or have any suggestions on how to fix it?

Yes, this is normal. NVidia doesn't consider -3FPS to be enough safety margin and they cap lower than that.

[jorimt]

Hi everyone,

I'm having an issue with my monitor and NVIDIA driver. I have G-SYNC enabled + VSYNC (only in nvcp) and the monitor runs at 390Hz. However, when I turn on Reflex + Boost to further lower latency and cap FPS below the monitor refresh rate, it locks my FPS to 351 instead of something close but below 390 FPS.

Has anyone else experienced this or have any suggestions on how to fix it?

Thanks in advance for your help!

PS: I don't know if this is the correct place to post or if I should have posted this under the XV252QF thread

As RealNC already menitoned, it's normal for Nvidia to auto-limit the framerate with G-SYNC + V-SYNC + LLM "Ultra" or G-SYNC + V-SYNC + Reflex, and the higher the physical refresh rate, the lower they set the limit.

At 240Hz, the limit is ~7% below the refresh rate (~224 FPS), and at 390Hz, it's ~10% (~351 FPS).

Now, while it's true that the higher the physical refresh rate, the lower you should probably set the limit due to frametime tolerances narrowing due to a faster scanout time, Nvidia is being pretty aggressive at 390Hz+, it seems. Why that is, you'd have to take up with them.

That all said, what is often misunderstood about my -3 FPS recommendation is it is a minimum recommendation, not a hard-and-fast rule. It's a starting point that takes into account the frametime variances of both your typical in-game and external limiter, and while it's usually sufficient for 240Hz or under refresh rates, it may need to be dropped lower at higher than 240Hz refresh rates (say to 3-5% of the physical refresh rate), especially if the limiter being used doesn't have the steadiest of frametime performance.

Then again, the difference between G-SYNC and no sync at 390Hz and higher refresh rates in both average latency and visible tearing artifacts begins to reduce to the point that G-SYNC isn't as useful as it is for lower refresh rates anyway, and once we hit 1000Hz, syncing methods will become virtually unnecessary, regardless of achievable framerates.

[RealNC]

Now, while it's true that the higher the physical refresh rate, the lower you should probably set the limit due to frametime tolerances narrowing due to a faster scanout time, Nvidia is being pretty aggressive at 390Hz+, it seems. Why that is, you'd have to take up with them.

Haven't tested myself, but I've seen reports that nvidia's limiter is very jittery at high framerates. Maybe that's the reason they use lower caps:

https://forums.guru3d.com/threads/lock- ... st-6113247

[jorimt]

Haven't tested myself, but I've seen reports that nvidia's limiter is very jittery at high framerates. Maybe that's the reason they use lower caps:

https://forums.guru3d.com/threads/lock- ... st-6113247

Sure, could be a factor, but 1) the auto-limiting behavior occurs both with the LLM "Ultra" combo, which uses the driver-level "Max Frame Rate" limiter, and with the Reflex combo, which uses an engine-level limiter per game, and 2) I found in previous testing that the occasional limiter overshoot will not affect average latency unless it occurs sequentially over a period of several frames. I.E. a frame exceeding the set limit here and there won't be enough to revert G-SYNC + V-SYNC to standalone V-SYNC behavior, etc.

That said, I'm sure Nvidia has their reasons, again, I just don't know the "why." It's possible it's also arbitrary, and their current auto-limiting algorithm just scales statically with refresh rate, causing a larger offset at higher refresh rates than otherwise necessary.