12x Vega 56 Rig = 24KHs cryptonight = 500MHs ETH / 1800W = 120€ electricity month (10cents/kwh)
6x Vega 7 = maybe 24KHs cryptonight = +-600MHs ETH /  +-900W?! = 60€ electricity month (10cents/kwh)

prices
sell 12x Vega 56 = 2700€
buy 6x Vega 7 = 4500€
------------------------------------
switch to vega 7 = 1800€
60€ less electricity / month = 30 months to equal


mhhhhhh.....