Updated: Solved: Why the new Mac Mini Won't Work With an Ultrawide Monitor

...and how to fix the problem

This article has been updated with corrections and new information, thanks to readers ZinZ and infeeee.

Second update: An article in The Register explains the reason these computers have resolution problems is because of a shortcut Apple took to rush out its new hardware: "ARM-based Macs use graphics driver code based on iOS and iPad OS, which do not need to support that many displays." Read the full article here: theregister.com/2021/12/03/apple_m1_drivers/

A few weeks ago, I got the CB3 ultrawide monitor from Acer. It is gloriously 32" wide and makes my video tutorials (of CAD software) easier to edit. The resolution is 3440 x 1440, which in shorthand is 5K 3.5K. 

My newish Dell laptop runs with the new monitor, no problem: just connect any HDMI cable between the two. Here's a pic of the Dell running Camtasia video editing software on the ultrawide.

Last week I got the new X-based Mac Mini. I need it mostly only when I write about CAD software that runs on MacOS.

The computer had a problem right out of the box, when it didn't really understand it was connected to an ordinary 1920x1080 monitor. The image was too big, so that I could not access the menu bar. After a while, I was able to reach the menu bar blindly, and after a few reboots the Mac finally displayed correctly. Not a pleasant out-of-the-box experience

Next, I hooked it up to the Acer ultrawide monitor, but no joy. The monitor stayed blank, sometimes complaining "No cable attached." You might be able to imagine the time I wasted trying to get it to work. I have an ultrawide monitor and that Mac would work with it, darn it!

1. I tried Apple tech support where two techies tackled my trouble. In the end, the final advice from Apple was, "Ask Acer tech support."
2. I tried Acer tech support, and in the end the final advice from Acer was, "Ask Apple tech support."

I did some more mucking about, and on the second day finally got the ultrawide to work, but at the wrong resolution. Here are the resolutions listed by the Mac for the Acer monitor: none match the monitor's native resolution of 3440 x 1440 (click image for larger image).

Update 2: Reader infeeee suggested holding down the Option key while clicking Scaled. (Hold down the Alt key, when you have a Windows keyboard hooked up to a Mac.) It worked! The action forces MacOS to list all resolutions available, including the native resolution of 3440x1440:

And here is the the Mac Mini's output correctly displayed on the Acer ultrawide monitor:

As Management Speak (@managerspeak) so eloquently put it this morning, "The problem is that you are running the latest technology."

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In my efforts to fix this problem, I came across important details at Apple's Mac Mini tech specs page, written confusingly. (Note that my Dell laptop supports three displays at once.)

• The HDMI port on the newest Mac Mini handles only 4K resolution. This is why the ultrawide monitor worked, but at lower resolution.
• The Thunderbolt port handles 8K. But I had no cable for this spec.

The Mac considers the HDMI port to be the primary display; one Thunderbolt port is used to provide the secondary display.

So, the new Mac with its X processor cannot handle what my year-old Dell laptop can: outputting more than 4K resolution out of its HDMI port the correct resolution for the monitor automatically. This makes me appreciate my Windows- and AMD-based Dell laptop even more.  A reader suggested that a higher quality cable might help, which I have ordered.

Then I found that 8K cables are rare. I finally found an 8K cable that handles Thunderport at one end with DisplayPort at the other. (The monitor has two HDMI and one DisplayPort ports.) I ordered it and await its arrival. 

Comments

[Zinz]

Sorry to break it to you. But while the cable might be to blame, the resolution really isn't the problem.
You have around 5 million pixels (3440x1440). This is well short of 4Ks 8.2 million pixels (3840x2160). Troubleshooting with other computers cables and monitors might be the way forward. But you are definitely not anywhere near 5k pixel numbers. Congrats to the wide screen though. I am running an acer predator X34 for years with the same resolution as yours and it has been a joy.

[infeeeee]

It should be something else. That monitor is not 5K, but something like 3.5K. 4K means, that the horizontal number of pixels are ~4000: https://en.wikipedia.org/wiki/4K_resolution

4K is officially 3840 × 2160 = 8 294 400 pixels. Your monitor is 3440 x 1440 = 4 953 600 pixels. So it has less pixels than a 4K monitor, so the mac should handle it.

I suspect the problem is the cable or some software settings. For non hdr, 60Hz data you need at least a HDMI 1.4 cable. If you want higher framerate or hdr than you will need even newer: https://en.wikipedia.org/wiki/HDMI#Main_specifications

I don't know macs, but I have a similar 21:9 monitor, and if I plug in computers randomly a lot of them can't detect its settings. So maybe you manually have to set up resolution, and it will work.

[infeeeee]

I always knew that at tech support most workers are usually absolutely incompetent, and they have no idea what they speaking about. Here is an article about how to set custom resolutions on a mac, yes 3440x1440 as well: https://www.alphr.com/custom-resolution-mac-osx/

The trick: you have to hold option... I'm not a fan of Mac, but i'm even not a bigger fan of official tech support. In my life I never had any success solving any problems except product replacement. They just copy paste the same basic troubleshooting guides, usually they don't even read your question... if they are human at all. It's possible that a bot was reading your question, they saw you mentioned acer and they automatically redirected you. Contacting tech support should be your last option, ask on some tech forums or on reddit and they can help you better usually.