Just run 1100 MHz on core and 2000 Mhz on memory and you'll fine. Undervolt some like 850 mV maybe.
Is 850mV is the safest undervoltage for rx580 gpus ? Cos some people are using 75 watts mining with their rx580 and I can't get the same watt power draw from my gpu, right now it's mining at 90watts with 850mV using wattman, is there something I'm missing here?
Rx580 can still go lower as 800mv but if you plan to overclock 820mv is the lowest I can go on this card with 79watt power draw and also the following oc settings
Cclock 1150 and Mclock 2170, getting 30mh with this settings on Ethereum