2018 Mac mini has Thunderbolt 3 Compatibility Issues
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Readers might remember that in my review of the 2018 Mac mini I noted some display syncing issues with NEC displays. While I’m no longer having issues and 10.14.4 seems to have helped (unclear if all issues resolved for all users), it seems that Thunderbolt 3 is flawed on the 2018 Mac mini.
Issue: bus-powered Thunderbolt 3 devices connected directly to the 2018 Mac mini spontaneously disconnect. The issue is not specific to any brand but it happens, for example, with the OWC EnvoyPro EX Thunderbolt 3, which OWC lists as currently incompatible with the 2018 Mac mini.
See also: MacRumors: Mac Mini 2018 External Drives Disconnecting (TB3)
The good news is that an Apple firmware update might resolve the issue.
I have some information direct from OWC on this isue, including a workround of plugging the bus-powered device into any other AC-powered Thunderbolt 3 device (such devices are rigorously certified, ironic given the mini’s failures). Examples include the OWC Thunderbolt 3 Dock or OWC Thunderbay 4 or any other AC-powered TB3 device.
- Issue only occurs when directly connecting bus powered Type C devices to the Type C ports on 2018 Mac mini.
- Zero issue using any of these same devices that encounter issue directly connected when same device is connected via another Thunderbolt 3 device in front of it first
All thunderbolt 3 devices are required to put 15W minimum power distribution (PD) on both ports, which the Mac Mini does, but the issue seems to be that the mini does not maintain the required PD power out. Peripheral makers only get certified if fully meeting this requirement without exception. The qualification/certification is super strict in general and even tighter for bus powered. We have to submit to Apple and Intel multiple samples of EACH capacity with the drive to be built with and get individual certification on each config. Each time we even want to just do a new version FIRMWARE on an already certified SSD blade - we have to resubmit before shipping with the new firmware version. AC powered is easier as don’t need to also cert drives… but for bus powered they certify drives all the way down to the exact drives we want in our device.
Workaround solution: if you have a Thunderbolt 3 Dock or other other powered Thunderbolt 3 device, run through that and no issues.
And ZERO issues with ANY other Mac model or PC model with Thunderbolt 3 today. issue is limited to the 2018 Mac mini… which I still believe is a fabulous Mac unit and huge leap in the right direction. Thank you Apple!
Expect this to be resolved by Apple via an OS update that includes firmware update for 2018 Mac mini. It might already be rolled into 10.14.4 update - which we (OWC) have just started testing with and will know pretty well one way or the other by middle of next week. We don’t want to say fixed unless we’ve full proven it as the failures had no problem repeating didn’t show within a consistent amount of time - sometimes fast within an hour or 30 minutes… sometimes would take day or longer.
Brian M writes:
Just wanted to write that I have been experiencing the same disconnects with my 2018 MacBook Pro 15-inch and G-Drive mobile Pro SSDs. 10.14.4 (and 10.14.3 I believe). I’ve been frustrated with this for quite awhile.
MPG: Interesting... mayb there is more to it than just the 2018 Mac mini.