so neither rx580 is suitable for new miners period...if u r just starting now it is WAY TOO late...u r better off spending on RTX30series. Best card that can be bought...lowest power usage and requires only an 8 pin. No problems with mine whatsoever....as usual.
RTX cards are still selling for higher price today it's not a good option for a newbie, ROI is way longer than those rx580 and 1660 super which are the lowest GPU for mining today, rx6600xt is another good choice.
rx580 graphics cards have not been sold new in stores for more than 1 year. Therefore, you will have to compare the used rx580 and the new rx6600xt video card. If I have the opportunity to buy 2 used rx580 graphics cards instead of one rx6600xt, then I will choose 2 used rx580 graphics cards.