i7, far and away... but that said you're better off with a video capture card then either. The amount of cpu power streaming video eats up will chew into your fps no matter what cpu you get. a video capture card is the only way to do it without seeing a hit to your fps. so get the i5 and take the $100 you saved over the i7 and spend it on a video capture card, that i5+video capture card will work far and away better then the i7 by itself.