Two Monitors but Different Resolution Options

So I have a question that I hope someone can help me with. I have a M1 Mac Mini with two identical 4K displays attached to it. Both are the LG 32UN880-B 32" UltraFine Display Ergo 4K. Obviously, one is connected via USB-C and the other is connected via HDMI.

When I go into System Preferences > Displays > Display Settings and set them both to “Scaled” instead of “Default for Display”, I get different size options. There are five options for each and if I hover my mouse over the sample box it will show the resolution that corresponds to it. Here is the breakdown:

Main Display (via USB-C)

1504 x 846
1920 x 1080
2560 x 1440
3008 x 1692
3840 x 2160

Secondary Display (via HDMI)

1152 x 648
1504 x 846
1920 x 1080
2560 x 1440
3840 x 2160

I currently have them both set to the 2560x1440 resolution but ideally I would like them both set a little higher. The 3008x1692 looks fine but that isn’t an option with the HDMI connected monitor.

I’m assuming this is an issue with the connections (USB-C vs HDMI) but its frustrating that I don’t have the same options for both, especially since both supporters the max 4K resolution. Does anyone have any ideas on why this is happening and how to fix it?


Ben Collins
Lexington, KY

Someone else might know why, but I bet you’ll see the resolution you want, or at least find a good option on both lists, if you option-click on Scaling to show more options.

SwitchResX might be an option.

The resolutions on the USB side are determined by the electronics in the cable and the laptop, while the HDMI resolutions are determined by the laptop electronics. So unless SwitchResX can do 3008x1692 on the HDMI output, there’s probably not much hope.

The monitor supports the resolutions internally. The issue arises from differences in resolutions that these three connections support: the monitor input port, the cable, the computer output port.

I had to spend time with my LG 27U testing various options connecting to my MBP 16". I found that I could only get all resolution and other options on the monitor the USB-C input on the monitor. The HDMI input on the monitor only supported a subset from the full range.

IIRCl, I also could not find any satisfactory technical specs with the full details to all input / output ports on the monitor So I was left to do the trial and error testing on my own.


I can’t explain why but it seems that your expectation that two monitors attached to a mini will be treated the same is what is wrong. On Apple’s M1 Mac mini Video Support page it says:

Simultaneously supports up to two displays:
One display with up to 6K resolution at 60Hz connected via Thunderbolt and one display with up to 4K resolution at 60Hz connected via HDMI …

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I think “up to” are the operative words there.
i.e. 4K on the 6K connection would be “up to” 6K.

Like the internet scams, “Make up to $1,000/min stuffing envelopes at home.”
Yeah, $0 is “up to” $1,000/min.

Still says to me that that the two connections are different in protocol and electronics so I would not expect two monitors to be treated the same.

Finding supported resolutions seems impossible.
But anyway, here is someone running 3840x2160 on two displays, one an HDMI and one USB-C–>HDMI from an M1 Mac Mini. So it’s doable.

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Just of today, I got two new Samsung U32J59 running on DisplayPort via a Thunderbolt3 to 2x Displayport adapter.

Both are running on 3840x2160 at 60Hz, and doing so very well.
They are sitting right and left of my old 2017 5K 27’’, and are connected to him as an extended Display.

So, if my old iMac could do so, without a problem, the M1 MacMini should do at least the same, I would guess…

Everything to do with external displays and Macs seems to be black magic at best. What shows up as an available resolution at any given time depends on (at least) the phase of the moon, what you had for breakfast, the weather, whether or not you have a cat, the answer to P ?= NP. I have a pair of 4K displays connected to one of my Macs and most of the time they work fine, but sometimes one or both of them will simply not offer the same set of available resolutions that they did just a day ago.


A lot of cables have built-in electronics now, which leads to a lot of unknowns when troubleshooting. It’s also why some cables are stupid expensive.
It’s more than just making stuff fit nowadays.

Here’s an example from Ars Technica.

I had 3 4K on native solution 3840x2160 on my Mini using Thunderbolt, HDMI and DisplayLink. All fine.

If you are using an older HDMI cable, seek to replace it with a newer one that states “ultra speed” and “4k” and likely your problems will go away.

Also look at Displays app. It will sort out all your resolution problems (provided the hardware supports them)

Thanks, everyone. I’m using the USB-C and HDMI cables that came with the monitors. The problem is not the maximum resolution. Both monitors can run just fine at 4K (3840x2160). The problem is that the options under the scaled values don’t match. I would like to run both at 3008x1692 but that is only an option on the USB-C monitor and not the HDMI one.

I have the Resolutionator app from Many Tricks but when I start messing with the resolutions, things get fuzzy. If I set it as “scaled” through System Preferences then it looks sharp.

What did the option-click trick show you for the HDMI connection?

It did reveal more options on but on the HDMI connection, the top two choices were still 3840x2160 and 2560x1440. No option on the HDMI for 3008x1692.

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tick the box Show all resolutions underneath the selection window

And also switch on High Dynamic Range. I find it easier on the eyes.

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