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Nvidia Freesync Broken

PostPosted: 17 Aug 2019, 23:25
by masneb
So I just bought my XF252Q and testing out the freesync compatibility with my 2080. This is repeatable, after playing HotS and I exit the first game I play the freesync seems to partially desync with input? Either that or the display on the monitor is broken. I'm not sure which this is. Alt-tabing in and out of the game seems to fix it, however running benchmark with Afterburner shows it's still either still slightly desynced (it goes up to 70 even though Afterburner still shows a max FPS of like 63~).

Has anyone witnessed behavior like this? The only reason I noticed this is because the menu is basically locked to roughly 60fps and when you're in game you can't tell as FPS fluctuates a lot more. So the implications could be a lot more widespread. I don't know if this is a HotS bug or something more general to Freesync. The only way to verify something like this would be with a highspeed camera, whether or not the refresh meter on the monitor is broken or Nvidias Freesync implementation is broken.

MSI is a pretty vetted application so I'm pretty certain (99.9%) that it's not wrong.

https://www.dropbox.com/s/u0ca7t8k1c0wn ... 9.mp4?dl=0

Re: Nvidia Freesync Broken

PostPosted: 30 Aug 2019, 20:44
by Chief Blur Buster
FPS meters in monitors can be buggy sometimes -- they are often framerate averages but sometimes they have bugs in them.

But VRR tech can definitely de-sync frametime-vs-photontime
- Power management delays
- Software bugs
- Rendertime variances (divergence between frametime-vs-presentime, which leads to frametime-vs-photontime divergence)
- Driver bugs
- Monitor bugs
- Granularity bugs

Frametime/presenttime is measurable by tools like RTSS/Afterburner and other tools. Usually presenttime:photontime stays consistent but things like power management & monitor bugs can cause a de-sync not measured by RTSS/Afterburner.

Blur Busters feels that frametime:photontime should be sub-millisecond accurate, as millisecond imperfections can become visible at very high refresh rates. 1ms stutters on 4ms refresh cycles begin to become slightly human visible. 1ms is 25% of a 1/240sec refresh cycle.

To help improve things
(1) Set higher priority for the game
(2) Turn off power management
(3) Put computer in Performance Mode
(4) Test game's VSYNC OFF versus VSYNC ON modes, as their modes may affect frametime-to-photontime during VRR.