Question about how Nvidia Reflex works

[Biladeiro]

Hey everyone.

So I was doing some test in some games and I want to understand exactly how nvidia reflex works and how I should be using it.

First of all, I have a LG C2 as my primary display (120hz gsync).

So I was playing Warzone and I noticed that reflex by itself didn't limit the framerate, it only worked when I had vsync on. Same with Overwatch 2 and games where I forced reflex with specialk. So if I understand it right, I should have vsync AND reflex on, right? If not, reflex just works by keeping the GPU under 100% load and the frame stack empty, but with tearing?

Also, if I want to use framegen, should I force vsync in the driver if the game does not support it? Because ik that nvidia framegen should automatically turn on reflex in most games, but that doesn't mean that the fps will be capped under the gsync top limit.

Thanks in advance.

[RealNC]

So I was playing Warzone and I noticed that reflex by itself didn't limit the framerate, it only worked when I had vsync on. Same with Overwatch 2 and games where I forced reflex with specialk. So if I understand it right, I should have vsync AND reflex on, right? If not, reflex just works by keeping the GPU under 100% load and the frame stack empty, but with tearing?

It doesn't matter. It's your preference whether you want vsync or not. If you do use it, Reflex limits the frame rate so that you won't get vsync lag. When your frame rate is below the refresh rate, vsync serves as an extra protection layer against tearing. But you won't actually be getting the normal vsync lag; this only happens if your frame rate goes very close to your refresh rate.

In other words, if you enable vsync but keep your FPS below your max refresh rate, input lag is virtually the same as with vsync OFF. If frame times are a bit unstable, frames will be delayed just enough as to hide the tear line below the bottom of the screen.

Also, if I want to use framegen, should I force vsync in the driver if the game does not support it? Because ik that nvidia framegen should automatically turn on reflex in most games, but that doesn't mean that the fps will be capped under the gsync top limit.

You can limit your FPS with frame gen using the nvidia panel, or with RTSS after changing the frame limiter mode from "async" to "Reflex" in the RTSS options. SpecialK might also work if it has a Reflex FPS limiter mode.

[F1zus]

It is interesting to check whether reflex reduces input lag under the condition of Reflex + Vsync compared to Vsync + FPS limiter In-game.

[bumbeen]

Reflex works by measuring the time it took the previous frame to be generated and then pausing the game thread for just the right amount of time to synchronize the cpu and gpu work so input latency is minimized.