The PSU should be a EVGA or CORSAIR 1200 watt , fully modular and Platinum rated like the Hx1200 from Corsair, this PSU can keep up 5 cards even if they are running near 200 watt but that is not the case because when you are mining Ethereum they are consuming 135 watt each from GPU-Z or MSI afterburner app.

I would advise you to buy 6x 1060 GB 3GB for 1200 USD which would be a better choice, the consumption would be much lower than with RX 580 and you can mine Zcash to get approximately the same amount as for 5x RX 580. Make sure to buy a good motherboard for mining, like ASROCK H81 PRO BTC which supports 6 cards easily.