the iMac Pro in return for a setup that I feel genuine affection for. I'm willing to take the performance hit vs. Since they didn't get updated this year, it was easy to eliminate non-Pro iMacs from consideration, and, while there are refurb base iMac Pros available, I decided I'd much rather pick out my own display and put together a modular system based around the new Mac mini instead. Having spent time with 27" iMacs (both a late 2009 and a 2014 5k, both i7s), I've found that I don't really like working with them - something about their monolithic nature makes me dread sitting in front of them for long stretches of time. So, I'm fortunate that my wife was in need of a "new" (to her) computer, as her (my old) late 2012 21.5" iMac was getting grumpy, so we did what we usually do: get a new machine for me, and hand my current machine (in this case, a mid-2017 3GHz i5 21.5" iMac 4k) down to her. From two ports of a single controller I was only able to get 2852 MB/s where you would expect something over 3000 MB/s. That's more than you could get through DMI 3.0. I was able to get 4857 MB/s from both controllers with a RAID setup. That is a bottleneck if you are using more than one device simultaneously.īoth controllers of the Mac mini 2018 have PCIe 3.0 x4 to the CPU, so they both have full performance.
The Mac mini doesn't have a graphics card.Īnother option is to have the Thunderbolt controllers connected to PCH lanes where there are a variable number of lanes, but the PCH is connected to the CPU using DMI which is similar to PCIe 3.0 x4 in the case of DMI 3.0 or it could be PCIe 2.0 x4 in the case of DMI 2.0. A graphics card can use all 16, or it can use 8 leaving 8 lanes for other devices.
The Thunderbolt controllers can be connected to the CPU lanes where there is usually at least 16 lanes available - this is where a graphics card would usually go. In the case of PCIe 3.0 x4, PCIe traffic over a single Thunderbolt cable is limited to 22 Gb/s or 2750 MB/s. Some Thunderbolt 3 controllers may have a PCIe 3.0 x2 (1969 MB/s) connection or PCIe 2.0 x4 (2000 MB/s). A Thunderbolt 3 controller can have up to a PCIe 3.0 x4 connection to the computer (3938 MB/s without overhead). The question is how much of that bandwidth can be used by PCIe traffic (the rest is used by DisplayPort traffic). Does having 2 JHL7540 controllers actually confirm and mean that all 4 TB3 ports on Mac Mini are confirmed to be 40gb/s?Īll Thunderbolt 3 ports of all computers are capable of 40 Gb/s.
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