Hi,

I recently started mining Ethereum with one GPU RX 580 Sapphire nitro 8gb, and it works good on 31 mh/s.
I am planing to buy 5 GPUs more for mining but I don't know which GPU I will buy. So I have two questions:

1. What is the best alternative when Ethereum mining ends?

2. What GPU is better than RX 580 Sapphire nitro 8gb so I can use it on Ethereum mining now and on alternatives when Ethereum mining ends?