No HiDPI after Sequoia update for 3840x1600 resolution

[B4rt0sz]

I have a LG 38WN95CP-W (3840 x 1600) monitor and use it with a MacBook M3 Max.

Before Sequoia update I could select HiDPI for 3840x1600 24:10 120Hz 10bit option. Now it is not possible.
From the hardware point of view everything is the same (monitor, cables, notebook), only Macbook had its update and BetterDisplay.

Does anybody have some idea why this happened?

Now I only see this HiDPI support:

[sebastian-bugajny]

I have exactly the same issue on LG UltraWide 38WR85QC-W with MacBook Pro M3.
Max resolution with HiDPI support is just 3008 x 1254

[B4rt0sz]

Hi Sebastian, in one discussion, @waydabber told me you can choose your native HiDPI resolution and change the refresh rate separately. The text is sharp, and the monitor uses 120hz as it should (I prefer the same refresh rate on Mac and monitor).
In my case, it looks like this:

[waydabber]

Yes, this is a hack - switching to an unexposed refresh rate sometimes works and helps get around refresh rate limitations (other times it might result in a black or green image). The reason for this is that apparently sometimes the hardware legitimately can't handle higher refresh rate due to some kind of framebuffer pixel clock limit but Apple utilized a more broad/blanket limitation there for all Macs, enforcing limitations even when the specific hardware would still be capable to handle the higher refresh rate. So in these cases switching first to the desired resolution at a lower refresh rate (which is availabe in the standard mode list) and then force a higher refresh rate using the Refresh Rate menu's unexposed refresh rate list helps.

[B4rt0sz]

@waydabber, I would pin that somewhere if possible or add it to some FAQs. It is a popular topic after macOS 15 and m4 macros, and many for sure are searching for it or asking repeatedly. Think about it ;)

[waydabber]

Indeed. I wrote it about somewhere at a Macrumors forum I think. Maybe the info should be a bit more accessible, but since it kinda works but not for all, I don't want to raise false hopes. :)

[sebastian-bugajny]

In my case I cannot get higher resolution than 3060x1275 in HiDPI mode. Native resolution 3840x1600 works only in LoDPI mode where text quality is horrible.

[icableo]

idem, with a Mac mini m4 pro. Native 3840x1600 is loDPI