30 FPS, while monitor receives a 60Hz information

[Anatharias]

Hello, I've sent this request to the technical support 8 days ago and I'm still waiting for a reply, so here's the detail of my support request:

I got the latest Mac driver 1.10.2 on Sonoma 14.5 (M2 Pro MBP) with a Targus 180 Docking station.

My monitor is an Alienware AW3821DW connected through HDMI. That monitor supports up to 85Hz,**VRR and HDR, while connected through HDMI on that very Mac.

Though the Displays preference panel indicates 60 Hz, the monitor indicates 60 Hz, the UFO framerate test indicates 60 Hz, the test however leaves no doubt as to what the frequency really is : 30 Hz

Odd is that I sometimes get 60fps, but I'm in no way capable of reproducing it.
If I select 85Hz in the Preferences Panel, the display goes black and blinks an image once every 15-ish seconds.

The 30FPS situation is quite annoying as the whole system is slowed down whenever something needs to be rendered as a moving image, like a window scrolling, a YT video
When I get the 60FPS, none of that happens...

Attached is the debug files that the displaylink utility generates

DisplayLinkInfo_Output_20240611_163555 = issue is present, 30FPS on a 60 Hz resolution
DisplayLinkInfo_Output_20240611_150910 = issue is no longer present, 60 FPS on 60 Hz, just after closing the lid.

Unfortunately, opening and closing the lid doesn't always solve the issue.

thanks

[dbienkowski]

Hi Anatharias,
Thank you for reporting this problem to us.
We will address it immediately as the information you have provided is well described. Can you just confirm if the problem also occurs when connecting your Alienware monitor via DisplayPort cable?

[Anatharias]

Hello, thanks for your acknowledgement.
I really emphasize on the difference between FPS and HZ

I haven't tried using DP ports out, since the DP port on the monitor is used by my PC. But either HDMI Targus output 1 or 2 are "working" at 30 fps.

I could try to snap a video showing the issue, but really if you cannot "see" what's wrong.

Definitely a driver issue, since out of luck, closing the lid made the display blink and 60 fps came back

thanks

[dbienkowski]

Hi,
In this case, video will not be necessary. The only thing we would need is confirmation if the problem also occurs when the monitor is connected via DP. If you could manage to switch cables even for a moment to confirm this we would be very grateful.

[Anatharias]

Hello,

The DP connection did indeed work as intended (lid opened or closed) and did provide a smooth 60 FPS experience, even the 85Hz mode was offered (out of 144 Hz), and provided a 72FPS-ish ufo Framerate test.

I hope you'll be able to fix this, as I really use the DP for my gaming PC.
Thanks

In case you'd need it, I've attached the EDID of the monitor, connected through HDMI on the Mac.

[dbienkowski]

Hi,
Thank you for your confirmation. We will address this issue and issue a fix in the upcoming releases.

[Anatharias]

Awesome, can't wait !!!

also, if I could suggest limiting the output to 60Hz (not offering any other resolution choice), that'd be nice, because it seems that the Displaylink chip embedded in the Targus 180US cannot display higher than a set frequency, based on available bandwidth (reason why I only got 72 FPS out of the 85Hz on Display port).
Also reason why the display flickers to black when set to 85Hz by default upon first connection to HDMI

Cheers

[dbienkowski]

Hi,
The chip with which the Dock 180 is equipped supports 2x4K@60Hz. Unfortunately, the monitor's preferences in macOS will also display higher refresh rates if the monitor offers them, but it will continue to operate in 60Hz mode, which can be checked in the OSD.

Thanks