with rx 580 you can play with your core voltage, basically start from adding 20-30 mv to your core, add 10 mv untill you see no difference in performance, put your core voltage on minimum and power limit at around -15%(undervolted card is much cooler and more efficient) you can downcloack your memory, for this algo you don't have to overclock your memory, set it at 1500 or even 1400, bios mod tutorials can be found on youtube, good luck!