LFC Refuses to activate

[johnsmith]

Having just acquired a 7900XTX and still doing a few test runs on it, I noticed something peculiar that I have seen happen in the past with nvidia, but with the latter it would usually resolve itself by switching freesync modes on the monitor... Not with this card though.

For some bizarre reason, regardless of monitor I use (Got an M32U and a 24G2U), LFC refuses to double my refresh rate over the framerate.
Is the framerate 60? Refresh rate is 60. Is it 55? Refresh rate is 55. CRU does absolutely fuck-all, pardon my french. Tried DP and HDMI both, with both changes on CRU, but nothing. Upping the minimum from 48 to 65 or even 70 has no effect. It still shows up at 58~65 when the framerate is capped at 60.

Happens in any game. First noticed it in Elden Ring with its hard cap. Then hopped on Starcraft Remastered and capped it manually through RTSS. And yeah... It's simply not triggering, which in turn is triggering me.

I have a 2080 Super lying around with which I could fool around with and check if it's AMD related but it's a PITA to have remove the support bracket right now and run DDU again.

If someone has any ideas, please chime in. Thanks!

[johnsmith]

From what I can gather, AMD's LFC does indeed only trigger when the framerate gets below the lower end of the Monitor's range (which is silly). The worst part being that increasing that minimum in CRU does absolutely nothing.

EDIT: I guess my question is: why is CRU unable to change the refresh rate limits reported to the driver? No matter what I do it seems like Adrenalin always reads the real VRR range of the monitor, ignoring anything I do with CRU.

EDIT 2: Apparently, the dude developing CRU confirms that 7000 series gpus do not currently allow custom EDIDs. Yet another issue to add to the list of AMD driver limitations for their series. It's impressive, really.

[ilsamiles]

It seems like you're experiencing an unusual issue with LFC where it's not effectively doubling your refresh rate over the framerate, even when using different monitors like the M32U and 24G2U. This can be a perplexing situation, as LFC is designed to smooth out lower framerates by syncing them with your monitor's refresh rate to provide a smoother gaming experience. It might be worth exploring the specific settings and configurations related to LFC for your monitors to see if there are any adjustments that could potentially resolve this issue.

[Chief Blur Buster]

Verify that MIN and MAX refresh rate is a 2.5x difference, preferably more. Narrow refresh rate ranges will prevent LFC from working 1properly.

Because of this -- raising VRR Min Hz artificially on 144Hz displays is usually NOT recommended (sadly).

The ToastyX method of min-Hz-raising trick to improve quality of inexpensive VRR/LFC (especially those with bad overdrive, other VRR issues, etc) -- is only mainly recommended for 240Hz and up displays, or certain situations where you don't want LFC at all (e.g. strobed VRR, emulators, etc). Such tweaks can backfire, if your VRR range is already too tight to begin with (e.g. 144Hz VRR displays).

Now, another situation of LFC disappearing is using a video cable, video mode (higher resolution, 10bit mode, etc), or video port that limits your VRR Max to 120Hz instead of 144Hz, creating a situation of a too-small difference between MIN vs MAX. Fix that first..

In some cases, intentionally lowering VRR min Hz, can help LFC to appear. Many 48Hz minimums can be lowered to about ~40Hz -- but not on all displays -- but can be useful to activate LFC more reliably if you're limited to 120Hz.

The chief issue is the quality of different refresh rates (frame rates) in the VRR range, can favour disabling LFC, or enabling LFC.

Raising min Hz for LFC is usually pretty harmless (and oftentimes beneficial) for 240Hz+ monitors, but very iffy for 120Hz! It can create nasty problems of LFC disappearing if the MIN-vs-MAX multiplier is too small (well below 3, I would consider 2.4x to be the absolute minimum, but I prefer closer to 3-4x minimum, which is why I prefer 240Hz+ before raising LFC above 60Hz.)