My 5x R9 280x rig gives 3.5Mhs at 1.5kW (scrypt), 1.6Mhs at 1200W (SHA3) and 100Mhs at 950W (Hefty1). Daily profitability from above are related to theese speeds. Price of 1kWh here is $0.22, so daily "profit" is around $1..
With 80Mhs You can mine roughly 23k SLOTHs in an hour at current diff.
Hmm, I've only mined about 37k at nicemining since my earlier post, and almost none of those are confirmed. Perhaps their wallet needs updating?
I'm surprised your hashrate is that high for Keccak - I had been lead to believe that for SHA3 there wasn't that much difference between AMD and NVidia cards, but you're getting 5x the hashrate per card that I am, for 25x in total. Does 80 MH/s sound about right for a 2GB GTX 760?