For me it's just a single Vega 56 alone right on pcie 16x. Dual "monitor" setup(144hz freesync + 60hz tv).

Asus Prime B350 Plus / Ryzen 1600 / Win10 Pro 1809(Os Build 17763.194, should be latest) / 2x4GB 3000mhz and 16000MB virtual memory on Samsung EVO850 SSD / CN 16+14(tried few others but no change other than hash speed decreased)

Just ran teamred for the night as I wasn't using the PC; otherwise it works wonderfully except the system lag.