Frame doubling occurs earlier than it should (FreeSync)

[Deleted member 143938]

I have a ViewSonic Elite XG270QC, a freesync monitor with an advertised range of 48-165hz (https://www.viewsonic.com/elite/products/XG270QC.html#specs)

However, I notice frame doubling kicking in at 55 frames according to the screen's OSD. Is this to be expected/normal?

 

[kalston]

It's probably better to have LFC kick in a bit earlier to avoid something as drastic as 48hz48fps >>>>> 47fps94hz which would look flickery if the panel can even handle it at all.

This will vary between panels and they probably settled on 55 based on internal testing.

As long as it looks and feels good during gameplay you should not worry about it.

 

[Chief Blur Buster]

I agree.

I like early-kicking LFC for many reasons:

- Less flickering effects (e.g. from GtG fade or inversion artifacts) becomes higher than flicker fusion thresholds. Bringing up menus no longer flicker.
- Faster cleaner GtG with additional repeat-refreshes since repeat-refreshes are also GtG-kickers. 24fps@72Hz has faster GtG than 24fps@48Hz.
- Less likely to accidentally create refresh rates below min-Hz (e.g. 47Hz), so less likely to black out monitor from bugs.

The key to eliminating LFC stutter is in a wide VRR range.

Low-Hz and high-Hz refresh cycles can sometimes look slightly different on less-optimized FreeSync panels (unlike G-SYNC Native), because of uncompensated refresh cycle fade effects (fade to white / fade to black, depending on panel technology -- since LCD has decay like DRAM decay), such as a slight 1% to 5% difference in brightness for min-Hz in the worst cases I've seen. Better panels are more immune to fade, but there are other advantages as listed above too.

55Hz-240Hz range means the LFC penalty is only 1/240sec, so you don't see LFC stutter. Games running at 30fps is a 33ms frametime. An LFC penalty on that is only a 4.2ms (1/240sec) delay to a 33ms frametime. Also LFC stutter error is the halftime of max-Hz, so your stutter is +/- 2.1 miliseconds on average for an LFC mispredict. That 2.1ms stutter is invisible in the stutter/blur of 33ms frametimes. Ginormously wide VRR range turns LFC stutter a non-issue.

Thusly, for 240Hz+, 280Hz, and 360Hz FreeSync monitors, I prefer LFC cutoffs at 55 or 65 or 70. Keep away from common frame rates (e.g. 24fps multiples or 60fps) so you don't have a modulating effect (rapid cycling into/outof LFC territory from minor frame rate jitter).

I use ToastyX to intentionally raise my LFC min Hz.