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Why I Might Have to Abandon the 2019 iMac 5K
Related: 2019 iMac 5K, 4K and 5K display, backup, computer display, iMac, iMac 5K, Mac Pro, Thunderbolt, Thunderbolt 3, weather events
The 2019 iMac 5K is a terrific machine that will serve most all users extremely well. Most users will never hit the limitations I describe here. So I still highly recommend the 2019 iMac 5K for most users, including myself when traveling my Mercedes Sprinter van.
But alas, its one shortcoming is coming back to bite me in the ass, that is, the single Thunderbolt 3 bus with only two ports:
- A single Thunderbolt 3 bus means that I can never run a 6K display like the Apple Pro Display XDR without hugely degrading performance of all other Thunderbolt peripherals (see Understanding Thunderbolt 3 Bandwidth). That is, a 6K display eats 30 Gbps of the 40 Gbps available on the Thunderbolt 3 bus, leaving a sluggish 10 Gbps available for data—USB speed.
- My standard work setup already has three Thunderbolt 3 devices on the bus {OWC Thunderblade, OWC Thunderbolt 3 Dock, LaCie Bolt}, leaving only 3 peripherals possible. If I were to add a Thunderbolt 3 display or any other peripheral, only 2 others would be possible.
- With only two ports, cabling is a mess. And it means I can never just plug in a USB-C anything without crawling under my desk and rooting around in the dark with a flashlight.
- Thunderbolt 3 bus disconnects are increasingly bad with only two ports on one bus. It makes the whole system unreliable when connecting 5 or 6 devices—I”m afraid to breathe near any of the cables.
- I like to to do multiple backups at once, but I can never turn on a chain of Thunderbolt devices, because none will show up if there is one too many on the bus. So I have to decable and recable to backup to all my backup drives.
The 2019 iMac 5K is such a strong machine that this limitation just stinks, a whopper of a design failure that need not have been. If this is Apple’s way of forcing people to the iMac Pro, then shame on Apple—every other pro and semi-pro Mac has dual Thunderbolt 3 busses with 4 ports!
Most likely I will have to move to whatever the next generation of iMac Pro is and sell the 2019 iMac 5K, as much as I otherwise adore it. The 2019 Mac Pro looks superb, but it is hugely expensive, and unsuitable for use for travel in my van (no display, power hungry, bulky, etc).
