Mac has never been very friendy with running multiple displays on their products.
The 2018 Mac Mini showed great promise after going 4 years without an update.
It features four Thunderbolt 3 ports, and HDMI port, and according to Apple, up to “two 4K displays, and a third on the HDMI port”.
However, unlike the iMac, Mac Pro, and Macbook Pro, these four Thunderbolt 3 ports won’t all work for your displays like you think they will.
In the past, I’ve used docks like the Belkin ThunderBolt dock and the Elgato Thunderbolt dock to add an extra display to my PC.
However, the new Mac Mini seems to have a hardware limitation that, despite having plenty of power and bandwidth to power 4 displays, will not allow a 4th display to work, even with docks or an externally powered dual display option. This is most likely a hardware or macOS limitation.
I’ve tried many different options; different docks, different adapters, different monitors, different resolutions; the max number of displays is always forced to 3, and there’s not a whole lot anyone can do about that according to Apple.
After chatting with 9 different Apple employees (5 on chat, 2 in person, 2 over the phone), I’ve been told that it absolutely not possible to run more than 3 screens on the Mac Mini, even with adapters or hardware.
I figured out myself that I can connect a 4th display with AirPlay and an Apple TV. This isn’t the most ideal solution, but it technically connects a 4th monitor and works fine. There’s a very slight cursor lag, but over ethernet, it’s much faster.
I’ve been Googling this all week, and found that this 3 display limitation is actually due to the Intel graphics chipset (Intel UHD Graphics 630), and not a software or Thunderbolt 3 limitation like Apple support suggested.
So, I started looking into the possibility of upgrading the graphics; by using an eGPU, which is fully supported by macOS Mojave.
After chatting with another Apple Senior Advisor (Courtney), she told me she is very confident that this will still not work, and it won’t add another display since the hardware is still limited to 3. She also said that eGPU is not supported by Apple since it’s modifying the hardware and something that Apple cannot recommend (Wait what? Apple supports eGPUs and even sells them in their stores: https://support.apple.com/en-us/HT208544)
Thankfully, I saw this guy’s video, where he was able to run six 4K monitors off of a single Macbook Pro Thunderbolt port and an eGPU:
So, since I have a spare RX480 graphics card lying around, I bought a Sonnet eGPU Breakaway Box, which is an enclosure that is Apple compatible and recommended on their website. If you’re interested, you can buy it here; I’m not taking affiliate commissions or anything: https://amazon.com/gp/product/B0764J5QVD/
Despite 9 different Apple employees telling me that I can’t add a 4th display to my Mac, I’m now very confident that I will in fact be able to do so, and that anyone else looking to do so can either do it by setting up a seperate AirPlay display by connecting it to an Apple TV (ever-so-slight cursor lag but great with movies and cheapest option), or an eGPU (expensive but best performance). If you were so inclined, you can actually connect many displays with this method. Here’s my desk with 4 displays working; I guess I did the impossible, even though this was supported by Apple all along!
I hope this helped someone who is looking to add 4 or more displays to their 2018 or 2019 Mac. These new chipsets have a shamefully low limit for monitors. Heck, the old 2012 Macbook Pro was capable of more.
I also hope Apple trains their employees better on Apple-supported options to add additional displays, since they all had no clue about eGPUs or Airplay. One senior advisor even told me over the phone that the info I was requesting on adding a 4th monitor was confidential; I wish I was making this up. Apple sells eGPUs in their store, and the manager told me that I wasn’t able to add a 4th display as well, when the solution to my problem was 10 feet away on the shelf.
My eGPU enclosure that I linked above came in the mail, and I was able to hook up all four of my displays to my RX480. It worked perfectly out of the box; no drivers or configuration needed, just plug and play. They are lightning fast and the eGPU only uses one Thunderbolt 3 port.
setGpu, a project started by “mayankk2308” from Atlanta Georgia, can help you automatically modify all of your apps to prefer using your eGPU instead of your onboard graphics. You can find that here.
It isn’t yet available for Mojave, but the dev claims that he is building a new version that will be Mojave compatible.
Update Feb 20 2019: setGpu now supports Mojave! I just tried it and it worked great. If it helped you, make sure you donate to his project as your donations make things like this possible.
Update May 6, 2019: If you are noticing your screen flickering, this may be your power management feature trying to switch back and forth between your onboard and eGPU. The latest Mac update removed this option from the “Energy Saver” settings for some reason, so you’ll need to open Terminal and type in this command:
sudo pmset -a gpuswitch 0
This tells your computer to set your “Automatic Graphic Switching” to 0 (off), and the “-a” value means to apply it to all situations; plugged in, battery, etc. Since the Mac Mini doesn’t have a battery the -a value will ensure it never tries automatically switching your display source on you. No more screen flickering!
If this helped you, or if you have questions / comments / concerns, please leave a comment below!