Well I've got a few gaming computers, here are the specs:
Obviously RAM and CPU and SSD's that are in them are overboard but each computer has the following:

MSI Z270A Pro Motherboards
2 Radeon RX 470 4GB GDDR5
650 Watts Corsair RMi Series RM650i

Wondering what software/OS should I install and how should I configure these?

Should I combine a few GPU's into 1 Rig instead of only running 2 GPUs per RIg?