Hi there
It's just a theoretical question since I don't have the money to do it ;-) However if you would built bigger mining rigs (let's say 30 - 60 cards), is it better to run small systems with 6-8 cards (Asus Prime z270, MSI Z170A, Gigabyte GA-H110 etc) or 13 gpu systems with a ASrock H110 Pro / Asus B250? You're a probably more flexible with smaller rigs regarding cards and psu but need more time to maintain the system. So what would be overall better would you say?
I own the MO B250 mining expert it contains 19 GPU lines and as of now it works with the celeron processor for my mining rig. Even 12 cards GPU MO also a fine to start a small mining rig. Please ensure that you are adding the Rx series cards such as Rx 470/580 both 4GB and 8GB are good.
This will produce almost 22 MH for mining eth with the 470 cards and 580 may give upto 30 MH.
I see above some suggested to have the best RAM and CPU. I wanna say you RAM need to have the DDR4 and above but processor does not matter to mine bro. Have that in your mind first.