[SOLVED] Confused about Thunderbolt 4

Oct 6, 2020
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I have done some reading and watched a lot of videos but none clearly answer my questions:

Does Thunderbolt 4 provide 40 Gbit of bandwidth to one or more storage devices while providing data to 2, 4k monitors at the same time? I understand that no single storage device will get more than 32Gbit.

I have noticed that some computers, such as the high end MSI Z590 boards, provide two Thunderbolt 4 ports with two DP inputs. Is it the case that one DP input will result in that signal appearing on both ports and 2 inputs will place both 4k data streams on both output ports?

Sometimes I see the word "port" being used and other times I see the word "bus". I am concerned that the 40 Gbit is a Bus limit and that this bandwidth is shared across these two ports. I presume that the 40 Gbit limit is for data on one cable leaving the host?

I am just generally interested, I do not have an application that requires these speeds. I was planning to add a Thunderbolt 3 card to an MSI Unify build and I noticed the add in card has two ports. I am now looking at the Z590 boards and noticed that some provide two ports on the rear IO panel. I just want to make sure that I understand its limitations. I do not anticipate a need for this capability but would rather have two TB4 ports than the single USB 3.2 Gen 2x2 that I see on the last generation of boards. If TB4 is operationally compatible there is nothing that I could plug into the USB 3.2 Gen 2x2 that would not work the same in the TB4 port, this enhances the attractiveness of the MSI Z590 boards. I would like to build a system that I can used for the next 5 years before my next upgrade.

Thank you for your considerations.
 
In the last 24 hours I have found my answers. It appears that TB4 is:
  • An interface containing two differential data paths in both directions. They provide 40 Gbit bandwidth in both directions at the same time.
  • An aggregator of data in one of three formats DP, USB or PCIe until the 40 Gbit pipe is full. This means that data flow from DP subtracts from other services.
  • The pin assignments are determined by the female connectors and are full symmetrical allowing the male end to be plugged in ether way. It does not even matter if it is clocked 180 degrees from the one on the other end.
The only part of my question that remains unanswered is if the DP data is applied to both ports on a two port system. My build is desktop workstation so this is not an issue for me. I will not be sending DP down this port. I would rather have the speed for large data files.

Thank you for your consideration.