Mac Mini 2018 Thunderbolt limitation

[yfile]

Mac Mini 2018 (and probably some Macbooks Pro with four Thunderbolt ports) DOES NOT support more than TWO thunderbolt devices working at the same time. No matter which port you use, Mac Mini 2018 can't recognise third connected Thunderbolt device. I tried SSDs and eGPUs.
Why there are four Thunderbolt connectors in Mac Mini if only two are working anyway? It is a good question. It is weird.
Anyone have an idea to how to get around this limitation?
iMac Pro use older Thunderbolt controllers (JHL6540) than Mac Mini (JHL7540) and does not have such issue.

 

[esatamacmodular]

check in at egpu.io for eGPU enthusiasts. I thought 2018 mini had 2 TB3 controllers .. one would think you could have more than 2 devices ... maybe not more than 2 eGPUs though.

 

[yfile]

iMac Pro has also 2 controllers and it works just fine.
I tested two eGPUs and one Thunderbolt SSD. It also doesn't work. Always the third connected Thunderbolt device is not visible in the system.
It look like it's been blocked by Apple in macOS. Or it is a system/driver bug.

 

[Stephen.R]

Maybe yours just has a fault? Have you contacted apple support about it?

 

[DeltaMac]

Have you also tried a third TB3 device through a self-powered dock of some kind (and not directly connected to TB3 port)

Maybe this article can offer some explanation... https://macperformanceguide.com/blo...erbolt3-2018MacMini-disconnects-OWCEnvoyProEX

I also am curious if installing the latest beta for Catalina (macOS 10.15), which includes new bootrom updates for many Mac models, might provide a firmware update for the 2018 mini that can help that problem. You can install Catalina on an external drive, does not need to update the system that is presently your boot drive. The firmware update (if there is one) would still be applied.

 

[ElectricPotato]

I thought 2018 mini had 2 TB3 controllers

It does. It should be able to connect 4 TB3 devices. Google showed someone reporting problems peculiar to the 2018 Mac mini TB3 ports but that is related to bus powered devices disconnecting.

This case is probably an oddity (bug) with the drivers and the particular combination of devices. Since this does not seem to be a known problem, contacting Apple is the only way forward. I'm sure Apple will try to blame the attached devices and the support for the device manufacturers will blame Apple. You just have to hammer on the fact that the devices work individually, in all the different ports, and only fail when the third device is inserted.

 

[yfile]

Have you also tried a third TB3 device through a self-powered dock of some kind (and not directly connected to TB3 port) Maybe this article can offer some explanation... https://macperformanceguide.com/blo...erbolt3-2018MacMini-disconnects-OWCEnvoyProEX

I don't have a self-powered dock at the moment. However I connected a Thunderbolt devices without any GPU/SSD mounted and the Mac Mini detect only two devices as well so I doubt it is related to a power problems.

I also am curious if installing the latest beta for Catalina

I tried latest Catalina Beta (19A546d). The same - only two Thunderbolt devices visible in Mac Mini System Report
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Maybe yours just has a fault? Have you contacted apple support about it?

Not yet.
It is not that one/two of the Thunderbolt ports doesn't work. They all work but only two at the same time. I tried different combinations and always the third connected is not detected.

I received a message from a friend that he can't make work more than two Thunderbolt devices in his Macbook Pro 2016.

 

[DeltaMac]

As the article that I linked says, there seems to be a problem with power distribution to the TB3 ports.
The article says you could try a work-around by using a self-powered dock.
You can try one after having two devices already connected. If the third device works through that self-powered dock, then that's an answer for you: the mini runs out of power with more than two devices attached. Connect additional devices through a self-powered dock. (As the article mentions, the iMac Pro does not have that issue.)
I know your particular symptom seems different (doesn't see the third device at all), but it may still be related to the power issue with more than two devices.

 

[yfile]

Ok. I'll try to use dock when I get one. Thanks.

Does anyone have three or four Thunderbolt devices and can test it with Mac Mini 2018?

 

[BJB Productions]

Ok. I'll try to use dock when I get one. Thanks.

Does anyone have three or four Thunderbolt devices and can test it with Mac Mini 2018?

Just wanted to chime in that this happens with my 2018 Macbook Pro. So it's not limited to just the Minis it seems. Annoying, because I ordered a Mini to alleviate this issue.

 

[yfile]

Oh sh*t. I was hoping there is something wrong with my equipment, connections or Mac Mini firmware. I really need 3-4 GPUs for a Mac Mini. It's great tiny machine.
Looks like some kind of ThunderGate. In this situation those four Thunderbolt ports in the Mac Mini and some Macbooks don't make any sense at the moment. I still hope this a software bug.

 

[oppastopa]

The whole point of having four thunderbolt 3 ports was to be able to connect 4 thunderbolt 3 devices. I have an LG Ultrafine connected, and a Apollo Arrow. I plan to add either another Ultrafine, eGPU, and/or SSD external.

If this was an 'actual issue' I feel like loads more would've reported it. Buying a 300 dollar dock shouldn't be a 'fix'

 

[thevidness]

hi everybody,

tldr: you need to daisy chain. connect just two tb3 devices directly to the mac mini and chain others to those two (when possible). i managed to get three tb3 devices running concurrently using this method.


i ran into the same issue as you. i tried connecting an egpu (rx 580 in sonnet box), a pci chassis with 3 pci cards (sonnet echo III box with blackmagic decklink, sonnet usb3 and sonnet 10gbit ethernet built into it) and a samsung x5 thunderbolt 3 ssd (as boot drive).
i had no success getting everything to work when connecting to three ports. but the solution was to connect the ssd to the downstream tb3 port of the sonnet echo III. now all three work as expected.

 

[Squuiid]

This is definitely an issue. I can’t run two TB3 SSDs simultaneously, due to power.
I can run one SSD, one eGPU and DisplayPort out by that’s it. A fourth device fails.
Mac mini TB3 ports are very limited it would seem.

 

[eelpout]

I posted on a similar thread that I have two external Vantec cases with simple 3.5" HDD's and they rarely get a valid signal after wake (or even boot) when plugged directly in the USB-C ports. If I unplug/re-plug then they are recognized. Something strange is going on as they worked fine with sleep/wake on a 2012. Until I find a solution they go through a powered hub.