Why is my Mac mini M4 Pro display resolution low and how can I adjust it?

Servant of Cats wrote:

So I'm guessing it is a LG 40" UltraWide (40WP95C) WUHD 5K2K Nano IPS Curved Monitor

In my case, it's an LG 34" 34BK95U-W UltraFine (flat panel), but I see the same issue. As one who used the 3840x1620 setting routinely and now finds it unavailable on my new 16" M4 Pro MBP, it's annoying. It's even more annoying because I frequently switch back and forth between that Mac (my personal one) and my work Mac, a 16" M1 Pro MBP, that does support 3840x1620. So now, the text sizes are different between the two every time I switch. Major PITA.

FWIW, my LG display is Thunderbolt 3 and connected as such, so it seems unlikely this is a cabling/bandwidth issue. Especially since older Macs had no problem in the same setup, obviously.

For what it's worth, "like 3840x1620" would imply the use of an internal canvas that had 7680x3240 pixels. A 32" Apple 6K Pro Display XDR has a native resolution of 6016x3384 pixels. So the mode which you want to use would require a canvas with about 22% more pixels than the total number of pixels on a 32" 6K display.

As you said in your other reply, the M4 Pro should have no problem with that...the M1 Pro doesn't, nor does the 2019 16" Intel Core i9 MBP that is my prior personal Mac.

Your supposition about the internal canvas is correct. When taking a full-screen screenshot with either of those other Macs connected to the display, the output is a 7680x3240 image.

I've submitted feedback to Apple on this, and suggest anyone else with this issue does the same:

Feedback - MacBook Pro - Apple

As a followup, there are apps that allow use of additional resolutions beyond what Apple offers, including SwitchRes X and EasyRes (though the latter seems to have gone AWOL). I tried SwitchRes X, and it does allow selection of a 3840x1620 on the LG display. However, the results are less than optimal. My first impression was that the text was not as crisp as I was used to, so I snapped an iPhone pic of the same block of text shown on the display with the M1 and M4 MPBs connected:

Probably obvious that the M4 with SwitchRes X is on the right. I suspect it's just directly scaling down on the M4 instead of starting with the larger canvas as is done by the M1 and i9 Macs. SwitchRes X does allow inputing of a custom base resolution for scaling, and I tried inputing 7680x3240 but it made no difference.

I've uninstalled SwitchRes X and will just hope Apple corrects this issue at some point.

@nickt5775 As of now the only real workaround is to buy the BetterDisplay app and create a ‘Virtual Screen’ with the desired 3840x1620 HiDPI scaled resolution, and mirror the ‘real’ display to it. You can Google this and find out how to do it. Apparently people are finding this acceptable in many cases; I would suspect that the more CPU horsepower you have (i.e. an M4 Pro Mac mini instead of an M4) the smoother the Virtual Screen would work.

Full 5K is 5120x2880 pixels. Your monitor has 5120x2160 pixels – in other words, ultra-wide aspect ratio obtained by "adding stuff to the sides of a 4K monitor" or "chopping off part of the top and bottom of a 5K monitor."

So I'm guessing it is a LG 40" UltraWide (40WP95C) WUHD 5K2K Nano IPS Curved Monitor .

If so, it has a pixel density of roughly 139 PPI. Text in non-Retina, native mode, would be uncomfortably small.

• At your preferred setting, text would be almost exactly the same size as on a 27" 2560x1440 monitor.
• At the "like 3360x1418" setting, text would be almost exactly the same size as on a 24" 1920x1080 monitor.

I'm not sure why your preferred setting went away – whether this is just a software issue (one that a future macOS update might remedy, or that you might be able to overcome with third-party resolution switching software) - or a change in the video support of M4-family processors (relative to M1/M2/M3-family chips).

For what it's worth, "like 3840x1620" would imply the use of an internal canvas that had 7680x3240 pixels. A 32" Apple 6K Pro Display XDR has a native resolution of 6016x3384 pixels. So the mode which you want to use would require a canvas with about 22% more pixels than the total number of pixels on a 32" 6K display.

same issue here with a Lenovo P40w-20 (LG panel) - works fine on a MBP 16" M1 pro with 3840x1620 - on the new Mac mini M4 Pro this resolution is missing (using BetterDisplay but with 60 Hz refreshrate as workaround) - VERY annoying

I use 5120x2160 40" (75Hz) display also. Like all others its native DPI is 139. Running it at 3840x1620 causes DPI to be 104 which many people find quite comfortable.

I mainly use it for software development and really like my display space. I would like Mac to be able to render HiDPI virtual resolution of 4096x1728 (111dpi). This is equal to windows 125% scaling (which it is by the way able to handle quite nicely). This is something that no M-chip or macOS version has not been able to do.

I know that windows and macOS rendering paths are quite different, but also as an end user, I think that I should not be required to think such differences but instead just get the resolution I want.

BetterDisplay has a GitHub issue thread that discusses this and has some technical details: https://github.com/waydabber/BetterDisplay/discussions/1268

M4 Mac Mini + Studio Display

Display 5120 * 2880

Default 2560 * 1440

You have a native 5120 * 2160 so a different aspect ratio. Try Show all resolutions on the Display prefs and see what is available? Failing that take a look at SwitchResX or EasyRes or etc.

Servant of Cats wrote:

For what it's worth, "like 3840x1620" would imply the use of an internal canvas that had 7680x3240 pixels. A 32" Apple 6K Pro Display XDR has a native resolution of 6016x3384 pixels. So the mode which you want to use would require a canvas with about 22% more pixels than the total number of pixels on a 32" 6K display.

On the other hand, as long as you limit yourself to two displays, the Technical Specifications for the M4 Pro Mac mini seem to say that one of them can have "up to 8K resolution at 60 Hz … over Thunderbolt or HDMI."

I would think that an 8K output would have the ability to handle the internal canvas for Retina "like 3840x1620" mode. But maybe I'm wrong …

Good point, we aren’t being totally accurate when we say that we want “3840 x 1620.” What we’re asking for is to use the “looks like” 3840x1620, but MacOS actually uses the full 5120 x 2160 res and smooths the fonts really cleanly with all those extra pixels.

Another way to state this:

5120x2160 on 40” 21:9 display is 139 dpi

3840x1620 on 40” 21:9 display is 104 dpi

3360x1418 on 40” 21:9 is 91 dpi

what we want is to use 139 pixels to represent a 104 pixel inch-sized object, which means it can have smooth edges.

The alternative currently being offered is 3360x1418 (91 dpi) which is clean but too big (most lower res monitors are scaled for 96 dpi)

Also if I have a second monitor at 96-100 dpi, fonts will look similar on both if we can use this setting

MatNeh wrote:

Good point, we aren’t being totally accurate when we say that we want “3840 x 1620.” What we’re asking for is to use the “looks like” 3840x1620, but MacOS actually uses the full 5120 x 2160 res and smooths the fonts really cleanly with all those extra pixels.

In Retina "looks like 3840x1620" mode,

• The Displays Settings, or "UI looks like" resolution of 3840x1620 would be what applications use when sizing text and objects.
• The internal drawing canvas would have 7680x3240 pixels. As wide, though not as tall, as native resolution of the panel on an 8K (7680x4320) display.
• The Mac would downscale the 7680x3240 pixel canvas to get 5120x2160 pixels worth of data for the display.

In "3840x1620 (low resolution)" mode

• The internal drawing canvas would have 3840x1620 pixels.
• The Mac would upscale the 3840x1620 pixel canvas to get 5120x2160 pixels worth of data for the display. Like with expanding a MP3 file to a full-size uncompressed CD-Audio-quality file, this would increase the total volume of data, but would not add any information to the signal beyond the 3840x1620 pixels' worth present in the canvas.

If your Mac supported both modes, and you switched back and forth between them quickly, you'd see the text becoming cleaner when you switched to the Retina mode, and less-well-defined when you switched to the "low resolution" one.

Just found this on reddit --> https://www.reddit.com/r/ultrawidemasterrace/comments/1gp15c0/apple_base_m4_supports_5k2k_and_3840x1620_hidpi/?rdt=43329

Hopefully they are solving the problem with 15.3. 🫰🏻🫰🏻

Same here. Utterly annoying.

My M1 MBP works well with the 5k LG Ultrawide, and 3840x1620 is a splendid resolution (72Hz).

BTW, it shows HiDPI on my tool (BetterDisplay), it looks crisp.

While I can select the same resolution on my Mac Mini M4, it doesn't show HiDPI, and it (indeed) looks worse. De HiDPI settings available are 5120 x 2160 (way too small) and 3008 x 1270 (too big imho).

I'm glad I'm not the only one, so it isn't an issue on my device.

On the other hand, I'd rather have a DOA as I could return and switch.

It's quite odd that the latest and fastest (M4) processor and the same OSX version) isn't able to use my monitor as should be. And that it beats the M1 (??)

Same problem here - MacBook Pro M1 Max: no problem. MacBook Pro M4 Max: 3840 x 1620 resolution is missing.

Monitor is the Dell U4021QW (5K2K curved widescreen). I reported to Apple.

Other mentions of this issue:

• https://forums.macrumors.com/threads/mac-m4-base-or-m4pro-any-luck-with-3840x1620-hidpi-with-a-lg-40wp95c-monitor.2442772/

There seems to be some confusion about whether this is a Sequoia issue or an M4 issue. I had Sequoia on my M1 Max and resolution was fine. Sequoia on my M4 Max and this resolution is missing, so it maybe a combo of Sequoia + M4

I have the same monitor and am experiencing the same issue. Everything works perfectly with the M1 Pro, but the M4 can't handle it. It seems like this might be a bug, and according to a thread on MacRumors, Apple is expected to provide a fix. I also reported this to support but they closed the ticket without providing any insight. I just wish there was a public acknowledgment so we would know it's being addressed.

BetterDisplay is in HiDPI mode (see Screenshot) - subjective there is no difference between this solution and the MBP M1pro with native 3840x1620 support (besides the 60 Hz instead of 75 Hz(i can't spot any difference)) ... but still annoying ...