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i300 TB4 - how does video get from GPU to TB?


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I'm looking at using a TB4 monitor with my i300 but I want to make sure this is a good idea performance-wise.  I think the i300 motherboard is a custom version of the MSI MEG Z690I Unify.  For that motherboard, it's necessary to route you GPU card's DP outputs into two DP inputs on the motherboard backplane for the video from the GPU to get to the TB controller.  I assume on the i300 that there is some internal header connection from the 3080 to the motherboard but want to make sure that's the case and that it's not something like the i300 TB4 output is only using the iGPU rather than the 3080.  Anyone know the answer to this?

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The TB4 ports are connected to the motherboard, not the graphics card.  So, your TB4 monitor would run of the motherboard.

Also, with TB3 you were able to use an external graphics card.  With TB4 this feature has been dropped.  I seem to recall that data transport can use more bandwidth of the 40Gb/s port using TB4 (75% in stead of 50%?).

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9 hours ago, User 1 said:

The TB4 ports are connected to the motherboard, not the graphics card.  So, your TB4 monitor would run of the motherboard.

Also, with TB3 you were able to use an external graphics card.  With TB4 this feature has been dropped.  I seem to recall that data transport can use more bandwidth of the 40Gb/s port using TB4 (75% in stead of 50%?).

I think I probably didn't explain it right.  Yes, the thunderbolt ports connect to a thunderbolt controller on the motherboard.  However the thunderbolt controller has displayport inputs that it takes and mixes into the thunderbolt output.  The question is where these displayport inputs are coming from?  On a standard MSI MEG Z690I Unify, the inputs are actual ports on the backplane that you connect via cables to your GPU outputs.  I'm trying to understand where they come from on the i300.

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  • 1 month later...

Just as a follow-up in case anyone else is trying to use a Thunderbolt-based monitor with the i300.  There are Mini DisplayPort inputs behind knockouts on the IO backplate that need to be removed.  Once this is done you can hook up a DisplayPort-to-miniDP cable between the 3080 GPU output to the input and this will enable the Thunderbolt outputs to send video and I was able to drive an Apple Studio Display with no problem.  Refer to the MSI MEG Z690I Unify motherboard manual for details.

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  • 1 month later...

I have been trying to get something from customer support about the thunderbolt controller used, the specific wiring of the TB connections, and any details I can to figure out why the TB on this PC does NOT in fact support the full set of features out of the box and is specifically limited in this case by blocking access to the ports. This also bothered me as when I purchased this model (i300) I assumed that the intel 12900k's iGPU outputs were wired to the TB lanes for the DP Alt mode and video output. But then when I tried my Asus XG17AHPE Portable monitor I could only get a signal by using the 3080ti's output and nothing but charging from the TB ports. Everything else of course was working fine but the ONE specific feature I wanted is artificially disabled because of them not simply including the cables to route the DP-in ports to the 3080 or atleast just put a sticker over the ports to let customers know this feature is not active out of the box like the whole specification was designed to do, BUT THE PORTS ARE IN FACT THERE! Instead they are hidden with no indication that they can be used and would also give even further use and expansion of the TB ports. After I read this I went and ran my finger along the back and can feel both the DP-in ports AND THE HDMI AND DISPLAYPORT PORTS!

I wanted to be able to use this machine as a streaming pc that basically made a dual system obsolete. I had enough CPU cores, RAM, Storage and connectivity. But one specific thing for streamers is to have a 2nd PC with a 2nd GPU available running either encoding the stream or just as screens for extra uses. I wanted to be able to use the intel iGPU to drive an additional 2 monitors without having issues running my G-Sync Monitor off the 3080ti. Had you not decided to check the board and find that it is in fact a Z690i Unity board I honestly thought I got a broken/defective unit.

My actual question is how or with what did you actually make the cut outs of the DP-in Ports so they are accessible? I would like to keep it as easy and clean as I can and not have like a massive hole or goofy looking cutouts on the back. Could you give some detail as to how you made those? Or attach a couple pictures of your IO ports?

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  • 2 weeks later...

I did the same thing you did which was to feel the depression under the backplate label skin where the hidden ports are with my fingertip and then used an X-acto knife to make a small incision in the center of it and then carefully trace around the edges of the opening.  When I was done, I had the two DP-in ports exposed.  I purchased a small DP to mini-DP cable from Amazon and used that to connect the DP out of the 3080 to the mini-DP-in under the TB port I intended to use.  That's all it took.  It appears that it is a metal backplate with the precise-sized port holes covered by an adhesive skin so assuming you cut the skin carefully with light pressure, the resulting opening is the exact size of the port.  Here's what the end result looked like:

spacer.png

 

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