is playing games under VRR / and / 40hz under 120hz the same thing? any experts can explain?
first of all almost no one actually plays at actual 40 hz
there are four ways to get a 40 FPS game
with VRR and LFC and framerate cap. you just cap to 40 FPS and VRR and LFC handles it. in this case it usually uses LFC to sync 40 fps to 80 hz. this is the lowest input lag option because there's no Vsync delay.
with VRR and framerate cap. you just cap to 40 FPS and VRR handles it. in this case it uses VRR to sync 40 FPS to 40 hz. this is the second lowest input lag option. it is laggier than LFC because you're getting more screen delay. it will also look horrible because most screens are not designed to run at 40 hz. it may even cause headaches due to such a low refresh rate. this is only possible if the screen has 40-144 VRR range
with 1/3 vsync. so screen refreshes at 120 hz (what consoles do often in their 40 FPS balanced modes,
even if you have VRR enabled). this is a high input lag option because there's a big Vsync delay. however it may appear smoother than VRR since you buffer so many frames with vsync, you end up with smoother framepacing in many cases
1/1 vsync at 40 hz. almost no one does this. almost no screen actually support 40 hz and consoles do not support 40 hz output either.
It's not. 40fps on full VRR "window" will most likely end up being 80hz with LFC, it won't look as good as 40/120 1/3 divide.
40fps with fixed 120hz is IMO the best. It's hard to set up 40fps on PC to be as good as on consoles, I tried it at some point and just gave up. Games don't support it internally (outside of FFXVI) and most of the softwarze to cap framerate don't create satisfactory results with this kind of framerate.
On consoles 40fps can look quite decent and nice bump over 30fps IF developers set it up correctly.
you can actually use 1/3 vsync through nvidia inspector. it is quite good actually but I don't often bother because I don't like the vsync lag myself. I prefer having less smooth but more responsive gameplay. anyway I just play uncapped with reflex anyways so it doesn't matter much
not that it matters but forza horizon 5, a plague tale requiem and dragon age veilguard are games that I know that supports multiple vsync modes