I can see on the pools some miners with crazy speeds i can't imagine that they are using such amount of hardware to get this speed , it seems also that the cards are not really loaded when i run any of the public miners like claymore or sgminer .....just asking if there is really something like that..
Public miners made by non-professionals for non-professionals.
Well I don't think it's that good. You need pretty high speeds in order to make one month ROI with any GPU. Private miners mostly have 10-20% improvement over public ones. You may say well 10% is not much but it is for people with large farms