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Mac mini M1 external display scaling option (HDMI/TB3)

Hi!

I also have a Mac Mini M1 and my display is a LG 27UD59. When I connect the Mac and the display via HDMI/HDMI I also have the issue that 3008x1692 cannot be selected via "System Preferences" -> "Displays", but via app "Display Menu". When selecting this resolution via "Display Menu", it is all blurry, as others have already said. When I connect my display via USB-C(Thunderbolt)/Display Port, I get 3008x1692 natively in the System Preferences, and it look great!! (But basically it is 6016x3384 using HiDPI, therefore it is not possible via HDMI because it only supports 4k.)

My problem is: When my display is connected via USB-C(Thunderbolt)/Display Port and my system goes to sleep and I want to use my Mac, I have to disconnect anything that's hooked up on the second thunderbolt port, as otherwise the display stays black and I cannot do anything. I don't have this problem when my Mac i connected via HDMI. There the system is responsive immediately. When using USB-C(Thunderbolt)/Display Port, the system works fine and normal, as soon as I disconnected anything connected to the second Thunderbolt Port. (After I disconnected anything on the 2nd Thunderbolt Port and the display came back to life, I can immediately re-connect the device and use it.)

Does anybody else have this problem?
 
Try a different cable? I have an LG 4k monitor. I have no issue with either HDMI or Displayport.
 
M1gelo said:
I can force the 3008 x 1692 resolution via SwitchResX or Easyres but text will be less sharp as it can not force HiDPI.
Click to expand...
It's blurry because you selected a low resolution mode (not HiDPI) of 3008x1692 which is scaled up to 4K.
The HDMI needs a 6016x3384 not HDMI mode in order to have a 3008x1692 HiDPi mode.

M1gelo said:
I think this is because of the way MacOS handles scaling. To use a 3008 x 1692 resolution in HiDPI it needs to use a resolution of 6016 x 3384 and then scale that down. This is too much for HDMI, that's probably why it doesn't work.
Click to expand...
This makes no sense. If the M1 can scale 6K down to 4K for the Thunderbolt ports (DisplayPort output) then it should be able to do the same for the HDMI port (It uses a MegaChips MCDP2920A4 DisplayPort 1.4 to HDMI 2.0 Converter same as the Mac mini 2018 so it means DisplayPort is also used for the HDMI output).

Akme said:
I tried SwitchResX yesterday and was able to select 3360 x 1890, but it was fuzzy/unusable. (Likely a function of the max resolution being off.)
Click to expand...
It's blurry because you selected a low resolution mode (not HiDPI) of 3360x1890 which is scaled up to 4K.
you need a 6720x3780 not HDMI mode in order to have a 3008x1692 HiDPi mode but M1 Macs don't add modes higher than 6016x3384 because of software or maybe hardware.

Akme said:
Are we thinking this is a software problem?
Click to expand...
Yes.

Akme said:
Well, having said that, I am able to set mine to 3840 x 2160. So, it is capable of going wider than 3008. It's the monitor as being read to have a 6016 ceiling that seems to be the problem.
Click to expand...
But 3840x2160 is a low resolution (not HiDPI) mode. You need a 8K not HiDPI mode to do a 4K HiDPI mode (and there's not much point in having a 4K HiDPI mode for a 4K display unless you're testing an app for 4K HiDPI support that may exist on an XDR display or 8K display for Intel Macs) but the M1 Macs don't allow modes greater than 6K.

Akme said:
I wonder if the testing was primarily done with the XDR, for which it measures 6016 x 3384, and did not contemplate (somehow?) other displays.

I suppose the other argument would be that Apple simply has no interest in supporting non-HiDPI setups looking ahead, so they put some limits in place to ensure, in their eyes, the best MacOS experience.

For it all, I suppose I'm just hopeful it was either an opinion that somehow shipped and could be undone or, simply, an oversight. But it does seem that a hardware barrier could also be the case.
Click to expand...
For a 6K display, one would contemplate 4K and 5K HiDPI modes (requires 8K and 10K scaled modes) but maybe the hardware is not capable of going through all those pixels to scale down to 6K. If it were a software issue, then I suppose someone could patch it so that the 6K limit is changed to an 8K or 10K limit. I think those kinds of patches are more difficult in Big Sur than they are in Catalina.
 
Hi Apple friends, I got the same problem with the HDMI and TB3 connection and the resolution issue. I use the BenQ EW3280U and reported the problem direct to Apple. Spend more than 3 hours on the phone with them. Hope they come with an answer soon.
 
lancastor said:
The resolution I need is not in the additional list.
Click to expand...
I got the same problem on the Mac Mini M1 16Gb, with the HDMI and TB3 connection and the resolution issue. I use the BenQ EW3280U and reported the problem direct to Apple. Spend more than 3 hours on the phone with them. Hope they come with an answer soon.
 
So I stumbled upon the same issue today. Only up to 2560x1440 is selectable to my 4K HDMI monitor.

But I only have one monitor connected, and would like ot use 3008x1692. Would the issue go away if use a USB-C to HDMI adapter? Or should I go USB-C to miniDisplayport (which is another option on my monitor)?
 
PBL_1 said:
So I stumbled upon the same issue today. Only up to 2560x1440 is selectable to my 4K HDMI monitor.

But I only have one monitor connected, and would like ot use 3008x1692. Would the issue go away if use a USB-C to HDMI adapter? Or should I go USB-C to miniDisplayport (which is another option on my monitor)?
Click to expand...
DisplayPort has more bandwidth than HDMI so you should be using that. 3008x1692 should be possible even with the HDMI option though, so I don't know what's going on there.

Show the "Frequency Range" values shown by SwitchResX. Show the timings known to the M1 Mac using the ioreg.pl script.
 
joevt said:
DisplayPort has more bandwidth than HDMI so you should be using that. 3008x1692 should be possible even with the HDMI option though, so I don't know what's going on there.
Click to expand...
Exactly. When I can run 3860x2160@60Hz without issues with HDMI, it shouldn't be a bandwidth issue. Maybe I'll try a to borrow a USB-C to HDMI 2.0 adapter to check if that changes anything.
 
So I have borrowed an USB-C to HDMI adapter, the Apple A2119. Now I can choose 3008x1692. And it is looking very good.
 
I have the same problem and it's driving me nuts. I have 2 BenQ PD3200U monitors. The first one is connected to USB-C and the second one to HDMI.
The HDMI monitor only offers 2560 x 1440 (too big) or 3840 x 2160 (too small). It also looks really weird when you have two same monitors next to each other and the resolutions do not match.

I hope someone can figure out a solution.
 
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This really sucks. I'm thinking about returning the mini M1 for this reason. Otherwise it's an impressive machine. But working with two 32" screens on different resolutions is a big no-go to me. Hopefully this can still be fixed.
 
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Would the 3008x1692 be supported with Displayport on the m1 Mac mini, using a USB C to Displayport cable?
 
I can confirm 3008x1692 (2x/Retina) works on a usb C adapter but NOT HDMI output. I have two 4k LGs and tried different cables and switched back and forth. Only the monitor with the USB C to HDMI adapter supports retina at 3008x1692, but both support native (1x) at full 4k or 3008x1692 just fine.

This seems like a software or hardware limitation on the mac chipset itself as the max output will still only be the monitor's native resolution. You can get 2x on that resolution using an HDMI cable from the USB C adapter but NOT the HDMI port out of the mac mini.
 
I bought a thunderbolt (USB-C) to HDMI cable to try since it seemed to work out for some of you, but it doesn't works for me. I still can only access 1x 3840x2160 or 1x 1920x1080, no HiDPI, same as straight with HDMI.
 
Holding alt and clicking scaled in display settings will make the computer detect the monitor's resolution options.
 
This is what I get when I press and hold "option" and click "scaled" on my 4K LG Ultrafine via HDMI

Screen Shot 2021-03-20 at 1.22.13 AM.png


And this is what it says about my 4K screen in the System Report screen.

Screen Shot 2021-03-20 at 1.24.15 AM.png
 
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I bought a Benq EW3280U today and I'm having the same resolution issue on my M1 Mac Mini.
The perfect resolution "3008 x 1692" is only available via usb-c cable. But I'm getting a max of 30hz somehow and not 60 via usb-c. And the hdmi is 60hz but it's either too big or too small.

Pretty bummed out tbh. :( Does anyone know any fix to all these?

usb-c vs hdmi
Screenshot 2021-07-15 at 11.31.38 PM.JPG
Screenshot 2021-07-16 at 1.56.18 AM.JPG
 
Sovon Halder said:
I bought a Benq EW3280U today and I'm having the same resolution issue on my M1 Mac Mini.
The perfect resolution "3008 x 1692" is only available via usb-c cable. But I'm getting a max of 30hz somehow and not 60 via usb-c. And the hdmi is 60hz but it's either too big or too small.

Pretty bummed out tbh. :( Does anyone know any fix to all these?

usb-c vs hdmi
View attachment 1806811View attachment 1806812
Click to expand...

Is there a function on your monitor that prioritise resolution instead of data speed? On the Dell it does. If you choose "prioritise display resolution" you can get 60Hz at 3008x1692 HiDPI via Display Port
 
When I plugged my new mini into my old HP monitor it was impossible to get a useable screen regardless of the settings. Only one screen was stable and that was far too large for the monitor, all other screen sizes just kept flickering on and off.
What cured my problem was attaching my HDMI cable to a cheap 6 in1 usb-c hub and card reader.
Now it runs perfectly.
Why, I've no idea, but it may be worth a shot.
 
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