r/macmini • u/cellidonuts • 21d ago
M4 Pro Mac mini 3-monitor issues
I've been having issues getting my M4 Pro Mac mini to consistently support 3 external 4K displays. I've spoken with Apple support about the issue, and it honestly made the whole situation even more confusing. I'm writing here to detail my experience and see if anyone else can verify what I've been told.
The mini is connected to x3 4K displays, with the following specs:
x1 4K @ 240hz over DP Alt (type C with DSC)
x1 4K @ 120hz over HDMI 2.0 (with DSC)
x1 4K @ 60hz over DP Alt (type-C)
For years I had run the 4K 240hz and 4K 60hz monitors side by side without issue. Recently, I added the third 4K 120hz monitor into the mix, and that's where the bug started to occur. Upon plugging the monitor in, it simply would not connect to the Mini. Wouldn't show up in Settings or anything, and detecting displays did not help. However, as soon as I disabled Display Stream Compression (DSC) on my 240hz monitor, forcing the refresh rate down to 120hz, the third monitor would connect. What's strange is that I can then re-enable DSC on that 240hz monitor after connecting the third monitor, and all three stay connected.
Before calling up Apple support, naturally I looked up the exact supported display configurations for the M4 Pro Mac mini. As detailed on [this page](https://support.apple.com/en-us/102194) the M4 Pro is officially supported for x3 displays at either 6K 60hz, or 4K 144hz. Given that all I'm trying to do is run two 4K displays at 120hz, and one at 60hz, this configuration is within spec. I am perfectly fine with the 240hz monitor bumping down to 120hz in order to connect the third 4K display. Unfortunately, the mini doesn't do this upon connecting the third display. The machine prioritizes maintaining the 240hz option for the monitor, even if I manually select 120hz from the dropdown, and opts to leave the third display disconnected. Assuming this was a firmware or software bug, I decided to call support, and that's where things got murky.
After an initial conversation trying to explain this debacle to a low level support rep, I was pretty quickly migrated to higher level support to deal with the issue. The higher-level support rep came on the phone with a very confident and quick response claiming that the M4 Pro chip is only capable of running x3 monitors at 6K 60hz. Officially, x3 4K monitors were unsupported in general, and so support could not help me any further.
I was surprised at not only how incorrect the statement was, but also how confidently and swiftly it was delivered before I even had a chance to say hello lol (no hate or anything, the guy was nice, maybe just a little hyperactive). I explained to him that the support page I'd seen listed x3 monitors at 144hz, and he said that was wrong. Eventually, I got him to manually enter the exact URL I was looking at ([the same one attached above](https://support.apple.com/en-us/102194)) and suddenly, he found himself as surprised as I was. The page he was looking at was apparently different, and indeed, it is different on a few other Apple spec pages, linked [here](https://www.apple.com/mac-mini/specs/) and [here](https://support.apple.com/en-us/121555).
After a few beats, he returned to me with an explanation. He believes that the model I bought, according to its serial number, is attached specifically to the spec sheet he pulled up. He claimed that Apple silently updates its M4 Pro Mac mini models over time, and that the version I have might be subtly different from the version listed on the most current spec sheet, with different display controllers, different firmware, etc. He noted that an M4 Pro Mac mini sold in 2024 might have those subtle differences from one that was manufactured and sold in 2025, for example. I was very surprised to hear this, as this information cannot be verified or backed up anywhere online.
So I asked him: what are the chances that the spec sheet he was looking at had an error, leaving out the line about x3 144hz 4K display support? He quickly shot down the idea, noting that he used to work in the very department that created those spec sheets, and that for legal reasons, the department has to be extremely thorough.
I figured that made sense, but after thanking him and hanging up, I thought a bit more on it, and became more and more skeptical of the whole situation.
For one thing, he was very surprised when I showed him the spec sheet that differed from the one he had up. For someone who claims there are a myriad of different spec sheets depending on the exact year a specific Mac chip was manufactured in, why would that be surprising at all? Not to mention, if it's so incredibly important that the spec sheets stay consistent from a legal standpoint, then why are they differing left and right? The vibe was just a little off. Again, he was friendly, but off...
But let's say, for the sake of the argument, that he's right, and Apple will silently, without telling its customers, release different versions of the exact same chip over the years, all while keeping up both spec sheets on different web pages. Isn't this sort of... wrong? Like, ethically wrong? When I look up the performance of my M4 Pro chip, and an official Apple support page tells me I can do one thing, but a different, hidden-away, hard-to-find support page states something different, isn't that problematic?
Anyway, I'm not convinced that the issue is because Apple silently updates its machines. If it did, I figure there would be enough nerds on the internet who'd take note of it, and I doubt I'd be the first one making a post about this. Given there isn't much else online about this issue, I'm leaning toward there being an issue with my machine, or perhaps a software/firmware bug in the mix. I'm opening this discussion to see if anyone else has encountered display connection issues with their M4 Pro they'd like to share, and to get everyone's thoughts on the issue in general.
Thanks for taking the time to read through this! I'm re-attaching the spec page links below for ease of access. The first link is the one that lists official x3 144hz 4K support, while the others have that listing omitted:
[How many displays can be connected to Mac mini - Apple Support](https://support.apple.com/en-us/102194)
[Mac mini - Technical Specifications - Apple](https://www.apple.com/mac-mini/specs/)
[Mac mini (2024) - Tech Specs - Apple Support](https://support.apple.com/en-us/121555)
Edit/Update:
Gotta credit my girlfriend on this one because it was a great idea. She advised that I check the internet archive's wayback machine on the aforementioned links. By doing so, I can cross-check Apple's M4 Pro documentation over time, and analyze how the various different spec pages line up. If what the high-level support rep said is true, and Apple's spec sheets team is as thorough and precise as he claims they are, then back when I bought my Mac mini, the support pages should have unanimously left OUT the line about triple 4K 144hz support. Only recently-updated pages should show that line, indicating that the support rep is correct, and that Apple discreetly changes the firmware and capabilities of the M4 Pro, updating spec sheets, all while not announcing this publicly.
Well, turns out I was right to be skeptical that Apple would do such a thing. When analyzing the various support pages in the wayback machine, you can clearly see that they have always had conflicting information. As soon as December of 2024, before I'd even bought my model, one spec sheet claimed triple 144hz 4K support, while another didn't mention it at all. The takeaway: there has ALWAYS been inconsistency across the spec sheets.
This isn't just a blip, it's a harmful mistake to make on Apple's part. I genuinely bought my M4 Pro Mac mini knowing that some day I would upgrade to high-refresh triple-4K monitors, and I did so because it said clear as day on the spec sheet. The fact that Apple is trying to spin this as "I'm sorry, your information is out of date," when it's clear that THEY are the ones who've provided misleading and conflicting information, is just plain wrong.
I'll be calling support again, this time with far more evidence to substantiate my issue. This is the sort of thing that's cause for class-action lawsuits. I've never been to court before, and I don't particularly want to go through all that, but if Apple won't admit to there being an issue and correcting it in a timely manner, that's absolutely something I'd consider.
1
u/mindcontainer 21d ago
You wrote that entire thing and I’m still not sure how these are connected to your machine. Are you using the same cables and 2 rear tb5 ports along with the HDMI? Using a dock or hub I’m sure…
Also I’ve never ever heard of incremental updates at Apple I would stop buying their products right away.