So I RMA a 1070 FTW and I see they are shipping me a EVGA GeForce GTX 1080 SC GAMING 08G-P4-6282-KB.  If I was a gamer this would be great, but I am not.  So before I put the 1080 on the open market then purchase a 1070 and have some change, what is this card good at mining in the cryptocurrency world.  FYI- I have three 1070's currently mining Eth.

Well I hope that is the case but my old card was getting 31.567 mhs of Ethereum, and in all my research it seems the 1080 will be geting 23-24 mhs, unless I am missing something.

1080 is a better card than the 1070 for most GPU mineable algorithms that are NOT ethash - like equihash (ZEC/ZEN/ZCL and such), lbry, Nist5, it's too long a list to continue here.
A 1080 WILL match or exceed the income level mining ZEC that a 1070 can manage mining ETH, abet it will use a bit more power doing so - at current price/difficulty levels.
1070 IS better at Ethereum mining - higher hashrate at a bit lower power used.
 
 

THANKS!!!  My mistake when testing was I was running my 1070's with my optimum Eth config, when I tuned for Zec I did get higher profitability.   3 x GTX 1070s:  Eth = 94.469/mhs 1% dev fee,  ZCash = 1478.34/sols 2% dev fee.  Using two separate calculators I get: CryptoCurrency is Eth = .0006847 eth/day, $3.38 profit/day, and Zec = .017 zec/day, $3.45 profit/day. WhatToMine is Eth = .007238 eth/day, $3.89 profit/day, and 0.000426 btc/day and Zec = .00158636 zec/day, $3.98 profit/day, and 0.000446 btc/day.  So I will keep the 1080 and sell one of my AMD cards.

I took the power trade-off under consideration in my costing; however, my rates were based off the numbers provided by the miner.  Since then, I have ran both overnight taken rates from the pools 8 hour average hashrate and Eth is slightly more profitable with the 1070s.
 
Coin  Rate  Pwr  Per  Pool Fee   Est. Rewards   Rev. BTC   Rev.    Cost   Profit
Eth   31.4   110 Day 0.000024  0.002378       0.000145  $1.25  $0.26 $0.98
Zec   457    110 Day 0.0001      0.004895      0.000137  $1.17   $0.26 $0.91
 
However,  I prefer to have the diversification of the two Eth and Zec, and this also allows me to run my AMD cards using Claymore dual for Eth/Verge, with the Nvidia at Zec using BMiner.  Also, for my original question, think I will keep the 1080 and mine ZEC because its much more profitable for that card.

Totally not profitable.
I ran my heavily overclocked GTX1080 FTW/i7 6700k fully watercooled system for a couple of days just for fun - used Nicehash.
Nicehash benchmark was high for this hardware.
It made less than a little over $3 in 2 full days.
 
Electricity is $0.15 Kw/h
 
Do the math......

I am doing ZEC and I have my 1080 doing 570/sols at Power avg 130w for avg 4.20 Sol/J, which averages a little lower than my 1070s which avg about 4.50 Sol/J.