RX 500 series was an updated Polaris version of the RX 400 series released in spring 2017.
https://en.m.wikipedia.org/wiki/Radeon_RX_500_seriesIMO, you are better off with the newly released RX6600 XT. Same hash rate as the RX 580 at 40% less power and a 3-year warranty vs a 4 year old GPU run hard in a Chinese warehouse. Those fans will probably be shot. Better resale with the newer cards and GPU availability has already started to improve and it will will improve more the closer the expected ETH POS merge date nears.
Yes with the release of the rx 6600 xt, it makes no sense continuing buying polaris, 6600 is 128 bit, very low usage x poalris.