I'm looking to get into mining. I already have one rig and it is performing decently, but I feel I need more.
I heard ETH's mining difficulty is getting harder and some people are switching over to mining Zcash instead. I'm currently running 6x RX 480's dual mining ETH/SC.
I want to build another 2-3 mining rigs, and want to make sure whatever I build will not decrease in performance mid->longterm. Would it be wise to build an Nvidia rig and mine alternative coins (other than ETH-based currencies) instead of building more AMD rigs?
Hi . In my opinion , if I had $40,000 , I would like trading them on buying/selling eth and anothers cryptocurrencies , I saw a documentary on a website and they told the Ethereum coin won't mine anymore , and I think the price for 1 eth will go less than 200 usd
But you have lots of coins for mining and if you really really want to invest in mining do it

By the way , nvidia will release a new video card specially for mining with 24mh/s , low price and low power usage , is named gp106-100 , you should wait for it

, but the stupid thing is that this video card has just 1 year warranty

and if you want to re-sell it will be hard , because I prefer to buy a normal video card and selling it to a gamer or another person , but if you buy this video card will be hard to re-sell them

Happy mining !
Actually the warranty is rumored to be only 90 days on these new cards, not sure where you heard 1 year.
As for ETH, it will switch to Proof of Stake, which is just another form of mining. Basically if you own a lot of eth, you can stake it in exchange of mining work. It's a very simplified view of things.
Myself if i had 40K to spend on mining equipement, i'd still do it now. There are other coins you can mine and make a profit out of, and having 40k of mining hardware will give you a nice edge over other miners.
That said, i'd go for 570/580s with 8gb of ram and mix it up with some nvidia gpus (those made for mining). I would also fo only 8 gpu rigs instead of 6 to lower the cost and wattage.