Now It's time for you to experiment with HDMI
https://forums.macrumors.com/threads/guide-hdmi-audio.1499797/
Maybe the behavior will change with log-in problems after this patch applied it worked on my GTX Mac edition with nv Quadro
I have booted on first (PCIe 1)GPU connected and then attached second (PCIe 3) screen on other GPU or vice versa
But never boot with all connected screens on different GPUs after driver install.
Once your configuration is established it may become very buggy if you try to experiment with different screens sometimes it breaks all the configuration .
In my case after attaching six different screens on two GPUs The configuration become unusable and breaked with one of the screens disconnected and changed resolutions, so be careful with
synchronization of different screens !
This synchronization features changed during the OS updates
(<13.4) so it's not The problem of the driver.
This driver was introduced before eGPUs operating system feature leaved BETA
In this scenario SwichResX becomes very handy.
I have login problems with all other drivers, and did not understand your results.
1Question 2x1070 but different brand do not log in with both connected to hdmi ?
2Question 3 different 1070 fe, katana, inno3d 2GB vram work only with one card connected per dvi ?
And finally make a screenshot of your McP Cuda POWERHORSE with benchmark like Vray that would be interesting!!!