2018 Mac mini + 3x4k displays no eGPU. Experiences?

binaryduke

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Jul 4, 2015
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Can anyone share any experience of using 2018 Mac mini to drive 3x 4K displays using the internal graphics only? I’m considering this configuration (no heavy video editing - desktop apps only) as a replacement for a CMP.
 

Stephen.R

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I have a a 2018 mini with 2x 4K displays, using just the iGPU.

I think a lot will depend on which displays you want to use. Running at the 'native Retina' (i.e. 'looks like 1920x1080' on a 3840x2160 panel) it runs two displays fine, and I'm pretty positive that's the 'standard' Apple use for specifying that the mini will run 3x 4k. If you happen to have a larger (physically) display, and need to use a scaled resolution, you're gonna be SOL. The iGPU will run 1 4K display at a scaled resolution pretty well, or 2 of them quite poorly. 3 I imagine would be horrific.

The other thing to remember is that one of the three supported displays has to be via HDMI - so you need to make sure at least one of the displays you pick connects via HDMI.

Oh and don't forget you need to upgrade the memory - the iGPU literally shares system ram, so things will go south quickly if you're tight on memory. I'm using 64GB, but I've seen reports that 16GB is enough for 4K, if you can afford 32GB that's probably safer.
 

binaryduke

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Jul 4, 2015
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Thanks. I wouldn't be using any scaling/retina. This would be driving 3x 32" 3840x2160 displays at native resolution. Good point re the shared RAM - thanks for that. Am aware of the HDMI connection requirement and the displays support HDMI, DP, mDP.
 

zerozoneice

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Jun 26, 2013
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I have a a 2018 mini with 2x 4K displays, using just the iGPU.

I think a lot will depend on which displays you want to use. Running at the 'native Retina' (i.e. 'looks like 1920x1080' on a 3840x2160 panel)
What options do you see in display panel? What does it default to, native 2160p one?
How do you access the "looks like...." resolution?

I'm asking because on my 1440p display (over hdmi), to get the "native retina" look i would need to set a 720p resolution...but it looks like crap, so it's not doing the 4x interpolation apparently
 

Stephen.R

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What options do you see in display panel? What does it default to, native 2160p one?
How do you access the "looks like...." resolution?

I'm asking because on my 1440p display (over hdmi), to get the "native retina" look i would need to set a 720p resolution...but it looks like crap, so it's not doing the 4x interpolation apparently
The default on these displays (and I believe most other displays with a suitably high PPI - certainly it's true on my 2018 MBP15) is "retina" mode. I have to hold Option and click "Scaled" to get the old-style list of resolutions, which has both "retina" scaled modes (all of which will end up sending a 3840x2160 image to the display), and the non-retina approach (where it's sending the resolution you pick to the display).

I'm guessing that you'd need the display to be no bigger than ~17" or so, for macOS to detect it has being "high DPI" and offer the retina scaling mode.


Screen Shot 2019-08-20 at 15.26.46.png
 

zerozoneice

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Jun 26, 2013
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The default on these displays (and I believe most other displays with a suitably high PPI - certainly it's true on my 2018 MBP15) is "retina" mode. I have to hold Option and click "Scaled" to get the old-style list of resolutions, which has both "retina" scaled modes (all of which will end up sending a 3840x2160 image to the display), and the non-retina approach (where it's sending the resolution you pick to the display).

I'm guessing that you'd need the display to be no bigger than ~17" or so, for macOS to detect it has being "high DPI" and offer the retina scaling mode.
hmm, are you using DisplayPort or HDMI?
I don't see those "low resolution" resolutions on my screen....still, it's a 27" 1440p display...at least 720p HiDPI should be available somehow, but i can't see it. It only lists it as 720p..(not even 1280x720). Default resolution for display is 2560x1440, but it looks...nothing as sharp as yours.
 

Stephen.R

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hmm, are you using DisplayPort or HDMI?
I don't see those "low resolution" resolutions on my screen....still, it's a 27" 1440p display...at least 720p HiDPI should be available somehow, but i can't see it. It only lists it as 720p..(not even 1280x720). Default resolution for display is 2560x1440, but it looks...nothing as sharp as yours.
I'm using DP, but your problem is that you're using a low PPI screen. 2560x1440 @ 27" is ~109PPI, using it at 1280x720 would make everything on screen comically big, and still wouldn't look that great, because the physical pixels are still quite large/low density.

As I said - the "Retina" modes only seem to be available (and only really make sense) on displays with reasonably higher than "normal" PPI (normal for macOS being ~110).
 

zerozoneice

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Jun 26, 2013
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I'm using DP, but your problem is that you're using a low PPI screen. 2560x1440 @ 27" is ~109PPI, using it at 1280x720 would make everything on screen comically big, and still wouldn't look that great, because the physical pixels are still quite large/low density.

As I said - the "Retina" modes only seem to be available (and only really make sense) on displays with reasonably higher than "normal" PPI (normal for macOS being ~110).
yeah, i know. I'm running a hackintosh partition on the AIO which has this 27" screen and there i manipulated the display modes to show 720p hidpi, as well as 1080 or even 1440p (by creating a fake 2880p resolution). While 720p was the clearest of them all (like in your screenshots), it was also the smallest :) so yeah, unusable but worked. Anything else in forced hidpi mode (like 1080 or 1440) looked a bit better than native 1:1 but nowhere close to sharpness and clarity of 720p hidpi.

So i guess on a 4K screen, 1080 in hidpi is the sweetspot, right?
(your screenshot above is 1080 hidpi, not 2160 native yes?)

THIS would be a nice AIO to be used with a Mac Mini ;)
 
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Stephen.R

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So i guess on a 4K screen, 1080 in hidpi is the sweetspot, right?
That would depend on the size of the screen, really. It's the "default" for macOS, certainly, because non-even-2x scaling is a performance issue, but even on my 24" screens, I find "looks like 1920x1080" to be a little too low (i.e. everything is a bit too big). One of these days I'll get around to ordering an eGPU (not much choice in-country so I have to deal with international payment + shipping + customs etc), and then I'll run them at the next 'stepping' up, "Looks like 2304x1296" - that's basically perfect, size-wise IMO, but it's too much strain to run two of them on the iGPU (it works but you get lag and weirdness).

your screenshot above is 1080 hidpi, not 2160 native yes
Yup, the 'default' setting.
[doublepost=1566318306][/doublepost]
THIS would be a nice AIO to be used with a Mac Mini
I don't think I understand. Why would you want an AIO to use with a mini?

Also, 4K @ 27" is a bit crap PPI wise.
 

zerozoneice

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Jun 26, 2013
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I don't think I understand. Why would you want an AIO to use with a mini?

Also, 4K @ 27" is a bit crap PPI wise.
well, because i still use windows a lot.
ahhh, your Dell monitors are 24" not 27", well that's why you have such high PPI.

Right now i have THIS with a High Sierra hackintosh partition...not too bad, but 144Hz won't work as i said over HDMI 1.4. Also i can't change monitor brightness for the HDMI connected monitor from Mojave. Other than that it rocks.

But for the future, am i correct to assume that for 24" one should go with 4K and for 27" with 5K (not too many options, very expensive)?

can you pls post a fullscreen shot of your desktop (with some safari window open, etc.) in both native (1080 hidpi) and slightly higher res (x1296)? The question is if on a 27" 4K monitor, the x1296 would also have the same "retina-like" sharpness as at x1080p
 
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zerozoneice

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Jun 26, 2013
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@Stephen.R got the Dell P2415Q today. It looks amazing (both clarity and size wise) on its default setting.
Now, do you use the default monitor profile or use the calibration wizard to adjust it more?
 

zerozoneice

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Jun 26, 2013
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yeah, the image seems a bit darker after the calibration wizard. Kind of almost like slightly more contrast. But is good.

the miniDP to DP cable that comes with the monitor doesn't fit in the mac mini, so i ended up using HDMI. First time after connection it was really sluggish, figured out it defaulted to 30Hz. After reboot went to 60Hz. I tried to disable HDMI 1.4 in the Dell HDMI menu, but it didn't move up/down between the options "enabled/disabled", only disabled was kind of selected in blue already.
 

Stephen.R

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A 2018 Mini doesn't have 'native' DP or Mini DP (earlier ones had TB1/2 ports which can operate as regular Mini-DP ports), but a USB-C to DP cable would work, if you wanted to go that way.

I haven't tried HDMI (I use mine with a TB3 to dual DP adapter to save a TB3 port) but it definitely seems more people report issues (particularly relating to 4k/60hz operation) with HDMI than DP.

You probably need to unplug the cable to change HDMI options (same is true for DP options - you can't enable MST mode while it's plugged in).
 

zerozoneice

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Jun 26, 2013
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A 2018 Mini doesn't have 'native' DP or Mini DP (earlier ones had TB1/2 ports which can operate as regular Mini-DP ports), but a USB-C to DP cable would work, if you wanted to go that way.

I haven't tried HDMI (I use mine with a TB3 to dual DP adapter to save a TB3 port) but it definitely seems more people report issues (particularly relating to 4k/60hz operation) with HDMI than DP.

You probably need to unplug the cable to change HDMI options (same is true for DP options - you can't enable MST mode while it's plugged in).
also how do you control the P2415Q monitor brightness from the mac mini, ideally using the F1 F2 magic keyboard keys? The "Nativedisplaybrightness" app doesn't seem to work anymore.
 

Stephen.R

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I personally, don’t.

I found an app that did it a while ago (I’ll try to find it for you) but I stopped using it, I seem to remember it not being very reliable.
 

LanTao

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Jan 1, 2018
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works, thx!
don't know if it's because i switched from HDMI to Displayport, but it finally works!
I found that I had to restart the program after granting it access to whatever it needed in System Preferences.

as i sidenote, the calibration over DP is different than HDMI.
also the calibration wizard creates a profile that it's identical to the default one.
in case of HDMI, the custom one was a bit darker, more contrast i believe.
Your monitor may have different settings between the two inputs if you tweaked them there before. Alternatively depending on many things like phase of the moon etc. the DisplayPort may be on v1.1 and have less bandwidth or HDMI may have picked a different encoding (4-2-2, 4-2-0, …) leading to different colours.
 

zerozoneice

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Jun 26, 2013
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i wonder how a 27" 4K interface looks like default (1920x1080 hidpi) on a mini, so i can compare to my 24" and see if it makes sense to move to 27"....i posted a new thread on this but no replies yet...
 

mjfutures

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Jun 17, 2014
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i wonder how a 27" 4K interface looks like default (1920x1080 hidpi) on a mini, so i can compare to my 24" and see if it makes sense to move to 27"....i posted a new thread on this but no replies yet...
it looks fine...
 

Stephen.R

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i wonder how a 27" 4K interface looks like default (1920x1080 hidpi) on a mini, so i can compare to my 24" and see if it makes sense to move to 27"....i posted a new thread on this but no replies yet...
It’s going to be the same picture but 3” bigger.

So slightly less crisp, slightly more my-first-numbers book.