Do Ryzen iGPU support DP MST?

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1

Can someone please tell me if Ryzen 9xxx iGPU support monitor daisy-chaning via

  • USB-C DP-ALT Mode +MST
  • DP MST

If the Ryzen iGPU do support MST, is this feature automatically supported on all X870 boards with either USB-C or DP port?

Thank you!

2

I don’t see any mention of MST in my motherboard’s manual (X670E proart)… I would think this depends on the motherboard (the iGPU just provides display streams and how they’re connected is up to the motherboard design). So best to check manuals of boards you’re interested in?

3

I’m here because so far I have not found any information regarding this topic.
My hope is, that someone here has the HW to test this or already has.

4

Sadly can’t test it for you. However it seems MST is a required feature of DisplayPort >= 1.2, if I interpret this correctly:

Now, it doesn’t say how many streams, so maybe just two?

I do know the iGPU can push 2x4k with no issues, but I had one HDMI and one DP.

5

Technically, if board mentions something like dp 1.4 - that should include mst to be complaint. But that’s in theory. In practice you’d better try a specific motherboard sample, if possible.

Edit: someone showed it’s possible

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6

Currently I’m looking at the AsRock X870E Taichi Lite. This board has only 1 HDMI (such a pity this is not DP) and USB4 for video output.

Obviously I can go HDMI-HDMI for the first monitor and USB4-HDMI or USB4-DP (both using DP-ALT mode) for the second monitor. I would prefer USB4 MST tough just to have clean cabling.

7

Nice :slight_smile: Thank you very much

8

Ok, here is the thing. If you look at the block diagram of this board, you’ll notice that the dual usb4 type-c ports are realized via a dedicated chip - ASM4242. According to it’s spec at least, it’s stated that it’s complaint with vesa dp 1.4a standard. And if I read that correctly - that might include MST.

9

I did not study the block-diagram before.
Now I’m wondering, if I ever want to passthrough the iGPU to a VM would I not also have to passthrough the ASM4242? Anyway that is another topic.

All the info we currently have strongly suggests that MST should work with this board.
Thank you very much @quilt and @alkersan for your support

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10

Interesting question but I don’t think so… If I understand correctly the display stream is passed from the GPU to USB4 port electrically and then just passed on – there is for example also a DP input on some motherboards or Thunderbolt cards to pass a GPU’s DP signal via TB/USB4 – in which case the signal is just added to the connector, no matter if it’s a dGPU or even a GPU in another PC…

Apparently it is possible to pass through the iGPU (search the forum), but you’ll need to dump the VBIOS for that.