these will be good enough i would say spend more on the speed of the ram than how much it is cause 24 gb is over kill but 12 gb is still a bit overkill
another thing i would say is spend more on stuff like graphics cards(i usually take gpu>cpu in price)
m4 ssd is very good imo but i think u should go a bit higher to 128 gb and make ur 1 tb into 500gb 1tb will last like a lifetime for me even with all my games(over 5 yrs and i havent even gotten half my tb loaded yet)
Your psu isn't going to cut it if you plan on leaving the option open for adding another card later on. With 580's you want a 1000w psu and with dual 680's an 850w psu. With that said the 680 would be the way to go...lower power consumption with better FPS.