Ive got 3 R9 290's mining away (and 2 R9 390's)

Eth youll get 29-31Mh/s Cryptonight is 850-900h/s

Still decently profitable. Youll just take a hit on the power cost side

You can use whattomine to see and just change poweruage. I use the 570 usually inplace of the 290/390 (its hashrates are a bit lower than a 290 but better to under estimate than over estimate). Then in the powerusage just change it to your actual powerusage (I just default to 300W)