LG 40WP95X-W / 40WP95C on M1Max and M2

[flotpg]

Hi,
I noticed that stock macOS (Ventura and previous) are offering different scaled HighDPI resolutions for my LG 40WP95X-W Ultrawide display depending on wich machine type (M1 or M2) it is connected to.

On M2 I have fewer options with the scaled resolutions. The M1Max offers me two more resolutions which resolut in more space / screen estate.

LG 40WP95X-W-on-M1Max:

LG 40WP95X-W-on-M2:

I just bought BetterDisplay hoping it can help me to fix this.

I'm afraid I didn't fully understand the concept of dummy-displays.
To get the same resolutions on M2 as on M1Max I need to create a dummy display.

• does this mean the native display runs at 72Hz (Checked via display's OSD > Infos...) but mirror is running at 60Hz?

Thanks a lot and best regards, Flo.

[waydabber]

Hi there - yes, the M1/M2 had a max 3072px limitation for horizontal HiDPI resolution as opposed to 3840px for the M1 Pro/Max/Ultra.

By creating the dummy you can use higher HiDPI resolutions, however dummies are locked at 60Hz. When you are mirroring, the mirror target display will match the refresh rate of the mirror source if such modes are exists for the native resolution of the display (and they most likely do exist for the LG Ultrawide). If the mirror target display's refresh rate can't match the mirror source then there is a visible and continuous stuttering (for example when you are moving windows around or scroll in Safari) which is undesirable.

Hope this helps!

[waydabber]

the mirror source in this case is the dummy which is 60Hz, the target is the physical display (this is where the dummy is being mirrored to). If you don't see stuttering, then it is at 60Hz but the OS won't show it anywhere specifically. :) Usually there is an option however on the monitor OSD which shows the current mode. It should show the native resolution at 60Hz.

[flotpg]

The monitor shows 72Hz. Strange?

[waydabber]

Strange indeed!

[flotpg]

From System Information:

Apple M2:

  Chipset Model:	Apple M2
  Type:	GPU
  Bus:	Built-In
  Total Number of Cores:	10
  Vendor:	Apple (0x106b)
  Metal Support:	Metal 3
  Displays:
Dummy For Lg Ultrawide:
  Resolution:	7680 x 3240
  UI Looks like:	3840 x 1620 @ 60.00Hz
  Main Display:	Yes
  Mirror:	On
  Mirror Status:	Master Mirror
  Online:	Yes
  Rotation:	Supported
Colour LCD:
  Display Type:	Built-in Liquid Retina Display
  Resolution:	2560x1664 Retina
  Mirror:	Off
  Online:	Yes
  Automatically Adjust Brightness:	No
  Connection Type:	Internal
LG ULTRAWIDE:
  Resolution:	7680 x 3240
  UI Looks like:	3840 x 1620 @ 72.00Hz
  Mirror:	On
  Mirror Status:	Hardware Mirror
  Online:	Yes
  Rotation:	Supported

Regarding "the M1/M2 had a max 3072px limitation for horizontal HiDPI resolution as opposed to 3840px for the M1 Pro/Max/Ultra" topic - is there any official documentation from Apple 😂 or did you gather these infos by testing?

[waydabber]

Hahh. Well, that is strange. I think there should be some stuttering then as 60Hz and 72Hz do not match up nicely. But if there is none or not one that bothers you, you should not look for it! :)

There is no official documentation regarding it, just by testing and checking the relevant data in the IO registry. These limitations vary by GPU on Intel macs as well.