1650$ pc for 1080p gaming

i agree with andy. gaming, ram speeds literally do nothing for you. you could stick with minimal ram speeds if you would like. you could do 2x 4gig and be good to go.
going with the i7 is pointless, but if the cost is similar to the i5, you may as well go with the i7.
 


Not exactly true. High speed ram affects the minimum framerates during gaming, so while you won't notice much if any improvement on average fps, your minimum framerates with high speed ram will rise significantly. This will improve your gaming experience.
http://www.overclock.net/t/1366657/ddr3-1600-vs-2133-is-there-a-difference-in-game