What impact would this have for games that are not running at such high fps though?
For my dad I bought a Freesync 75Hz monitor and a Quest 2 (although we're waiting for a better gpu to really exploit the later).
So if I understand you right, you need to set a limiter 1FPS higher than the headset refresh rate? Do you know why?
In my case it's tricky because the headset is at 90hz but the screen despite being freesync is at 75hz only so should I just set the limit it at 91fps nonetheless and run vsync off for the monitor? Or everything Vsync with no limit?
This is a bit more complicated but basically:
For freesync/gsync monitors you need the limiter to be set at least 3 fps below the maximum Hz. But you can set the limiter lower if you want. It just needs to be within the freesync/gsync range. Not sure what's the range of that monitor, most 75 Hz monitors tend to be only "freesync" from 50-75 Hz for example.
3 fps because all limiters have fluctuations and you don't want the fps to fluctuate over 75 fps. That would either cause tearing (no vsync) or input lag (vsync).
But you need the limiter to be ABOVE the Hz of the VR headset. VR headsets always use vsync (afaik it's forced, you can't set anything there! But it's very low input lag.. I never fully read into this topic...).
So if you'd limit below the Hz of the headset, it would drop to half of it. So 45 fps with inserted, artificial images in between to have "90 fps" for the always 90 Hz.
Oculus Rift calls this "asw".
That's why I suggested 91 fps. Most headsets run at 90 Hz so the limiter won't interfer with the headset. Most monitors have 100 Hz or more. So the limiter would be low enough for all these monitors.
Can't I set different settings for VR and monitor modes?
Sadly not. In-Game limiters don't make a difference between VR or monitor, riva tuner doesn't make a difference and I'm not sure about the graphics card's limiters, but I don't think they have such an option...
I'm not sure I understand, why would the stuttering not be noticeable with a non variable refresh rate monitor at 144Hz? If I only reach 60fps for example, why would the screen behave differently than a 60Hz one here?
Sorry, I have so many questions about this!
When you draw it on a paper. 144 pieces per second above 60 pieces per second, you'll see for how long a tearing border would be visible. It's very short.
The ratio is 2.4.
Dropping down to the lowest "round number", this would mean:
12x refreshing the monitor
5x new frame
(144 to 60).
Or in ms: 6,94ms refresh cycle, 16.67ms fps cycle.
Or from another perspective:
Without any sync, the new frame from the GPU will just be inserted to the refresh cycle of the monitor. The monitor refreshes from top to bottom and at 144 Hz, this takes 6,94ms to complete.
Due to no sync in my drawing, you will have about:
1. tear: 4ms
2. tear: 2ms
3. tear: 4ms
4. tear: 3.5ms
The tearing border will be visible during my "filled out" areas.
Very not mathematical but it really shows what's happening!
With vsync, the new frame from the GPU would be held back until the next refresh cycle. The issue there would the input lag from this but also an irregular pattern:
First frame would be displayed for 3 refresh cycles, the second frame would only be displayed for 2 refresh cycles!
The 3rd frame would be displayed for 3 cycles and the 4th frame again for 2 cycles.
You would definitely see the stuttering...
But would you spot the tearing boarder that crawls down on the monitor from top to bottom for only 2-4ms? I didn't... It doesn't look like "tearing". More like some glitching on some objects where you would spot it.
With freesync/gsync however, the monitor would go to either:
120 Hz and show each frame 2x
60 Hz and show each frame 1x
And to close on this:
If you take a 60 Hz monitor and limit the fps at 60 and don't use any sync, you might end up with this:
Correction:
In this case the tearing border would be close to the top of the monitor and be always in the same place.
But most of the times, monitors (or limiters) are not perfect so the tearing border would slowly crawl to the top or the bottom. Each refresh cycle a little bit...
When you have fluctuating fps, the tearing border will move around on the monitor.
