flagbender wrote: ↑20 Jun 2023, 09:31
Some monitors have higher processing lag at non-native refresh rates. I've seen here that VRR reduces this processing lag to minimum.
VRR doesn't necessarily reduce processing lag, but allows you to effectively simulate lower refresh rate operation while still retaining a higher physical refresh rate.
1. 120 FPS non-VRR at a 120Hz physical refresh rate = monitor refreshes 120 times per second, with each refresh completing in 8.3ms.
2. 120 FPS VRR at 240Hz physical refresh rate = monitor refreshes 120 times per second, with each refresh completing in 4.2ms.
In other words, VRR allows you to "bypass" the extra processing latency (and any other issues) of the lower physical refresh rates on the given monitor model by still using the highest available physical refresh rate.
flagbender wrote: ↑20 Jun 2023, 09:31
What about a case where I manually set a non-native refresh rate, but the monitor is working in Gsync or Freesync mode?
Ideally, you should never lower your physical refresh rate when VRR is enabled, and instead use an FPS limiter to reduce effective refresh "rate."
Lowering physical refresh rate with VRR will simply reduce maximum scanout time (delivery speed of each refresh), increasing overall frame delivery latency, regardless of framerate.
flagbender wrote: ↑20 Jun 2023, 09:31
1. a) What if I set Windows to 240Hz but with Freesync enabled - would 240Hz+240fps have closer to 8ms input lag or 12ms?
VRR has no control over the scanout time of the current physical refresh rate (only how many time the scanout process repeats per second), so the above scenario will retain whatever processing latency (and any other issues) the 240Hz physical refresh rate has on that monitor.
flagbender wrote: ↑20 Jun 2023, 09:31
b) And a sub-question, if the monitor is in Freesync mode, is that engaged at all times, or does the content displayed have to actively be engaging the VRR to get the QFT-like behaviour?
The former.
flagbender wrote: ↑20 Jun 2023, 09:31
2. My example assumes this particular monitor has fixed scan rate. Does anyone know if it has scan rate multisync instead?
The closest thing to that is VRR + max physical refresh rate + lower framerate = lower effective refresh rate while retaining scanout time of max physical refresh rate.