Interesting.. What about motherboards that have onboard VGA / HDMI? It needs to be disabled and use a GPU with 8GB instead?
No, on board works fine.
I'm gonna test it tonight. I have rig running on an AsRock H81 Pro BTC R2.0. I currently have x6 RX 580 8GB GPUs. But I'm going to disable onboard graphics, run display from a 8GB GPU and swap x2 RX 580 8GB GPUs for x2 RX 580 4GB and see if that works.