Before you buy a new PC.. you definitely need to invest in a better ISP you wont be able to stream even the lowest settings with your current Down\Up speeds.
skateman brought up a point that i didn't even look into, the minimum running requirement for the 780 is 600w. You definitely need to get a 750w+ for some overhead.
My EVO 212 CPU Fan is incredibly quite so i think its fine.
If your going just for gaming the i5 4670 is more than enough and is very cost effective, if you want future proofing i'd purchase the i7 if you have the extra money to splurge.
Besides not having an SSD and the above points, your build is perfectly fine.
edit: please make sure the case you choose fits your GPU.
Also something you should take note of, "lets suppose you have a 500 W power supply, a system that pulls 250 W at full load, and is on 8 hour a day running at full load all the time(unrealistic but makes for much easier math), that puts your PSU at 50% load so its going to be at peak efficiency.
Power drawn from the wall with each PSU:
Basic - 312.5 W
Bronze - 304.9 W
Silver - 294.1 W
Gold - 277.8 W
Platinum - 271.7 W"
So, depending on how long you're going to be running your PC for the day i'd suggest getting one of the higher rated PSU's
on that note, since you'll be streaming and probably for 6+ hours per day i'd buy this one;
http://www.newegg.com/Product/Produ...3r-_-Power+Supplies-_-SeaSonic+USA-_-17151087
seasonic in my opinion makes the best PSU's.
edit2: the Gigabyte GeForce GTX 780 Ti does have custom PCB's.