AMD Radeon RX Vega 56 eGPU output sync issues

So I am running a timecode window video on all my 3 outputs of the Vega 56 eGPU with 4k 60 separately on 3 monitors and they are sometimes randomly not frame accurate or synced in time. I made sure all the monitors were set correctly and they are the same line of monitors plus I have my GUI monitor out of the same eGPU. That being said is there anyway to get those outputs frame accurate and synced to play perfectly on time?


  • A few questions to better understand your issue :
    - How do you measure is your outputs are frame-sync ? By eye ? With a slow-motion camera ?
    - How much is the delay between outputs when the problem happens ? One frame ? A few frames ?
    - What connection do you use : DisplayPort ? HDMI ?
    - What is your machine ? MacBookPro Touchbar 2018 Radeon Pro 560X ? MacMini 2018 ?
    - What is your macOS version ? 10.14.6 ?
    - Do you have the issue if you only display a "Stripes" shader on your outputs ?
    - When you have the issue, is the FPS stable (see menubar "Output" to show it in Millumin) ?

    Thank you for your answers point by point.
    Best. Philippe

  • edited November 2019
    This problem is also what I have encountered, but I have not solved it, because the graphics interface of the mac system is independent and cannot be locked. Win can be locked. So in theory, using other software on the mac, arena, madmapper, etc. are the same, but when the graphics card is large, the problem is more obvious, and when the graphics card operation is small, it will not be seen. I don't know if millumin has any solution. The best solution is that the mac system can lock the graphics card output. Now I am using FX4 to solve the synchronization of 4 1080p60 monitors. But the lock between the three 4k did not find a way, I hope millumin or mac can provide some help
  • Hello @Eason,

    If you have some spare time, could you answer the same questions ?

    I've been able to run 3 x 4K@60 frame-sync outputs from such an eGPU, but on macOS 10.14.6 (see this post).
    Of course, Apple doesn't support frame-sync officially, but there seem there was a lot of improvements recently.

    On another side, we 're currently testing Decklink 8K Pro to see if multiple 4K outputs can be achieved (so far 2 x 4K@60 seems ok, but need more testing).

    Best. Philippe
  • edited November 2019
    Sorry, I don't have an egpu test. Because I have always had a question, the bandwidth of TB3 is only 40G, will it limit the operation of GPU or Decklink 8K Pro? Because 4k is 12G, 8k is equal to 12*4
  • Hello @Eason,

    We're talking with Blackmagic engineer about Decklink 8K Pro : we want to know what could be the maximum output we could get out of this device.
    We'll share the result on this post.

    From my tests and with latest Millumin beta : I can output 2 x 2160p60 from a Decklink 8K Pro connected to a MacBookPro Touchbar (Radeon Pro 560X). I was able to playback 2 x 2160p30 HAP movies as well.
    We're working to find more optimizations, but this might be the limit via Thunderbolt 3. Waiting for Blackmagic answer.

    Best. Philippe
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