Fiber if you get a 760 then your safe for life.(nearly)
Will a 7790 run bf4 medium
if you are NOT running 1080p monitors (ie. 1366x768 or 1600x900) then yes, yes you can. you might even be able to stretch it all the way to max detail + no aa with 40+ fps. if you are ,however, running 1080p then medium might be the sweetspot for it.