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A question about Freesync flicker workaround

Posted: 16 Feb 2023, 07:22
by OverCHAOS
So basically, I'm experiencing an (apparently common) issue that causes the screen to flicker under certain conditions when enabling Freesync on a monitor with a VA panel. It would usually manifest itself in game menus and during loading screens, but also during gameplay whenever there is a spike in frametime while the FPS is hovering around 60-65. Such jumps in frametime are so tiny that you could only see them on a frametime graph, but they would still cause Low Framerate Compensation to kick in and the screen to flicker.

Following this guide https://www.displayninja.com/what-is-fr ... lickering/ as well as a few other posts online, I tried decreasing Freesync range using CRU, but the usual values they recommend for Nvidia users (going from 48-144Hz to 80/90-144Hz) didn't fix it for me. Only when I changed it to 100-155Hz (since I'm using a 155Hz monitor) did the flicker stop completely.

So my question is: what's the downside of running it like this? The way I understand, below 77 FPS (half the refresh rate), LFC would kick in effectively "doubling" the frame rate into the 100-155Hz VRR range thus eliminating screen tearing. Also, between 100 and 155 FPS, Freesync would function normally. So the only issue is that between 77 and 100 FPS, there'd be no variable refresh rate. Am I correct?

Re: A question about Freesync flicker workaround

Posted: 18 Feb 2023, 18:22
by Chief Blur Buster
FreeSync range edits are usually not compatible with NVIDIA, you have to do it on an AMD card.

Other workarounds will have to be done;

Re: A question about Freesync flicker workaround

Posted: 11 Apr 2023, 19:02
by Case
That's strange, in my experience they work on nVidia just fine, it's just that LFC acts a bit unpredictable as to when exactly does it kick in, as it is different than it would be on AMD card, plus both the lower and upper values seem to affect it. So for example with my current monitor, the original Freesync range is 48-240, but LFC would already kick in at around 58 Hz, which is a bit too high, so it does cause VA flicker. If I raise the lower limit to say 75, then it does kick in at around 85 Hz. Based on that alone it might seem like LFC kicks in roughly 10 Hz above the lower limit, but if you try to lower the upper limit as well, this value goes down as well and the difference between the lower limit and the frequency when LFC kicks in gets smaller.

So you have to experiment a bit and see what Fressync range works best for your needs. For example I want to stay above 120 Hz if possible to tame overdrive a bit, and I often limit my games at 90 fps (a good compromise for my setup), but I also want to run at 200 Hz max, since that's the limit for my monitor to use 10bit color, so I'm using the range of 92-200 Hz, which covers the 90 limit nicely with some headroom for fluctuations, giving me around 180 Hz with better overdrive and no VA flickering, but doesn't require me to go over 200 Hz and lose Freesync.

And I've used edited Freesync ranges with several different monitors and nVidia GPUs before as well, so it doesn't seem like my current config is an anomaly or something.

Re: A question about Freesync flicker workaround

Posted: 04 Jul 2023, 05:11
by Chief Blur Buster
Good to know -- it wasn't the case originally (in earlier drivers)