eGPU Testing

My current setup:
2018 MacBook Pro 2.9 GHz i9 with 32GB Ram / Mojave 10.14
Razer Core X with AMD Sapphire RX580 8GB Card
"Prefer External GPU" is checked (New Feature in Mojave).The GUI is running on a 1080p monitor connected to the eGPU. Two Outputs going into an E2. First output is DisplayPort 3840x1200@60 and the second output is 1920x1080@60 via HDMI.

Looping two 10 second ProRes 422 videos and about every 30 seconds, the frames per second drop from 60 fps to around 35 fps then back to 60 fps. Would anyone know what would be causing this? It';s pretty consistently happening almost every 30 seconds.


  • Currently trying on Millumin 3 beta version. Was also happening on Millumin 2.

  • Think I found the culprit. Mojave was changing the desktop in the background. Will continue testing.
  • Hello @HardwickM,

    Thank you for the info.
    Let us know the results about your eGPU. Also, be sure to read our post about good practices here.

    Best. Philippe
  • Frame rate still drops during playback. Goes down to around 40fps and comes back to 60fps randomly. But I am still running videos from my main drive as I don't have access to a TB3 external drive. This is if I am running one video on one canvas or four videos on four canvases. I don't think Apple is quite there yet with their support for eGPU's.
  • Hello @HardwickM,

    Did you try to use HAP or H264 codec ?
    They should more suitable than ProRes-422, especially to be transfered from your drive to the eGPU.

    I'm not sure a TB3 external would change anything, but let us know it it does. Thank you.

    Best. Philippe
  • I converted them to HAP and had the same results weather I had one video running on one canvas or four videos running on four canvases. I think the problem lies with Apple and the way the handle the throughput of the TB3 pathway. I'll give H264 a try when I get to testing again.

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