Came across a strange issue today in the game FFXIV, running on fedora 44 and KDE 6.6.5. I have a 75hz monitor that is configured to use freesync, and I don’t really have any issues in any other games, but in this one in particular is giving a very strange issue - if my monitor brightness (using kde display configuration) is set to 100%, then clicking the right or left mouse buttons (i.e. anything that hides the in game cursor) is giving me frame pacing stutters. vsync is enabled, and the issue does NOT occur if mouse 4 or 5 are clicked (because they do not hide the in game cursor). What is wild is that if I set the brightness to 99% (or basically anything except 100%), then normal / expected behaviour is observed - see screenshots below:
Brightness set to 100%, stutters are visibly observable in game every time I press the mouse:
Game runs under proton / xwayland. I have tried various proton versions and playing with GPU / CPU scheduler / clocks etc. I have been pulling my hair out with this but it seems like some kind of bug - this is the only game I’ve come across where it shows up, and it’s entirely reproducible across 2 of my computers (both run fedora 44).
Does that monitor have an external power supply or is it an internal one?
If it’s external, see if you can find another power supply with the same voltage but higher maximum current. If the frame pacing goes away, it may be that the original power supply couldn’t supply the needed amount of current for sustained 75Hz at max brightness. This happens with cheap monitors on occasion, where the manufacturer tries to save as much money as possible by providing lower quality power bricks that only just barely meet the requirements for the monitor to be able to do what it claims. I’ve seen claims of cheap modern day 144/180/240Hz monitors with similar issues and some have claimed changing the power brick fixed it.
Could also be an internal power issue from the power supply on the PC, but that’d probably still present itself regardless of backlight brightness.
EDIT: After rereading your post I noticed you mentioned this only happens with FFXIV.
Try disabling vsync and limit the framerate to 75 with gamescope or mangohud instead. See if it makes a difference.
It is perhaps a monitor issue, because I am able to reproduce it across 2 computers - one has an intel cpu and the other AMD, but both computers have the same model of monitor (unfortunately I don’t have anything else to test with). They use a normal psu plug straight into the wall - there is no external brick. The only way I’m able to get the stutters to go away with 100% brightness and vsync / freesync enabled is to limit the FPS to around 73 (i.e. such that the dips don’t throw the pacing off). If I test without vsync and limit FPS to 73 / 74 / 75 then the frame times are ok but mouse clicks make the screen tear… as if freesync is not enabled properly, but it most certainly is
Having the brightness set to 99% is a fine workaround for me, it’s just a rather strange quirk. I would never have figured something like that could cause actual frametime issues, as if the monitor is somehow able to apply backpressure to the gpu buffer? Or is that intentional freesync behaviour? I do wonder if some of the obscure posts about this issue are due to something similar… it seems like another solution is just to use a software rendered mouse, but the extra latency is pretty unbearable to me
Is this something that KDE would ever investigate / fix, or would it basically be put down to a device quirk
Yeah, that is a fairly simple workaround with not much impact.
If I test without vsync and limit FPS to 73 / 74 / 75 then the frame
times are ok but mouse clicks make the screen tear… as if freesync is
not enabled properly, but it most certainly is
Does your mouse have motion sync or Frame Sync in the case of Razer mice?
I don’t think so - mouse is a razer viper ultimate, but I’ve tested with a steelseries rival 3 and some cheap wireless logitech - no behaviour change. also changing polling rate makes no difference
