why dont u check for seasonic psu they are cheaper and they make psu for corsair
why get 590 do u have 3 monitor setup and better change the mobo as old mobo are never desgined to support graphic cards with huge power demanding cards and u will get more performance from 2 gtx 570 and have similar costs.
Whici cpu u are using as a weak cpu can cause a cpu bottleneck and the gpu would become waste as u cannot u its full potential
for gpu get the asus as the make the best gpu after evga
for 2 580 u would need a 850w 80+ and above gpu like corsair hx 850 80+ silver or seasonic x 850 80+ gold
make sure u have a big and ventilated case which could accomulate a 590 and a huge psu and have nice air flow like cm haf series and cm storm series which are aimed at gamers.
A personal note if there is constructron going on nearby then it is better to use a case with air filters as my cpu heatsink is clog