3 FPS Less Than Target = Why

[Joel D]

Hi, so I've heard it here before in passing on other subject threads. So wanted to ask this directly and have more deeper explanation as to why here in a dedicated thread.

So exactly why and what benefit do we get when we set our max frame rate to 3 less than target ? For instance I heard when setting your monitor to 240hz, and your game settings to 240fps, to then set "max frame rate" in the Nvidia CP to 237fps. So everything is set to 240, but then you cap the max frame rate in the GPU Panel to 237fps. I'd like to know why, and also what am I suppose to gain ?

I've tried this both ways, and honestly can not tell any difference that anything different is happening either way. lol So, curious if this is suppose to always make a difference, or only sometimes ? Or, am I doing it wrong ?

[jorimt]

Hi, so I've heard it here before in passing on other subject threads. So wanted to ask this directly and have more deeper explanation as to why here in a dedicated thread.

First off, just to be clear, the "-3 FPS Limit" recommendation only applies to VRR (G-SYNC, FreeSync).

G-SYNC 101: Closing FAQ...
https://blurbusters.com/gsync/gsync101- ... ttings/15/

I still don’t get it, then why do I need an FPS limit with G-SYNC, and why does the limit have to be below the refresh rate? Why not “at” it?

G-SYNC adjusts the refresh rate to the framerate. If the framerate reaches or exceeds the max refresh rate at any point, G-SYNC no longer has anything to adjust, at which point it reverts to V-SYNC behavior (G-SYNC + V-SYNC “On”) or screen-wide tearing (G-SYNC + V-SYNC “Off”).

As for why a minimum of 2 FPS (and a recommendation of at least 3 FPS) below the max refresh rate is required to stay within the G-SYNC range, it’s because frametime variances output by the system can cause FPS limiters (both in-game and external) to occasionally “overshoot” the set limit (the same reason tearing is caused in the upper FPS range with G-SYNC + V-SYNC “Off”), which is why an “at” max refresh rate FPS limit (see part 5 “G-SYNC Ceiling vs. FPS Limit” for input lag test numbers) typically isn’t sufficient in keeping the framerate within the G-SYNC range at all times.

For standalone V-SYNC off, you don't need an FPS limit to prevent sync-induced input lag, as it doesn't sync.

And as for standalone V-SYNC, you instead ideally want to limit your FPS as close to the refresh rate as possible, as to prevent refresh rate/framerate mismatch, since V-SYNC is a fixed refresh solution, and, unlike G-SYNC, forces the render rate to match the display rate:
https://blurbusters.com/howto-low-lag-vsync-on/

[Joel D]

Ahhhh, got it. Only when using the syncs. Understood. Thanks for clarifying that.

And thanks for clarifying its benefit/purpose for when you are using a sync.