I am actually going the opposite way of 750, and am going for a more power efficient approach for now (prepare for texas summer) going to take some of the knowledge from this guide. https://bitcointalk.org/index.php?topic=395004.msg4260763#msg4260763

Once i get that settled though think ill go for 750 if possible and take advantage of the cold weather as long as i can.

The case fans are ~kinda expensive, 13 bucks a piece, but 166 max CFM and ~37 dba (The GPU fans are WAYYY louder. these things are actually pretty quiet. Long term i'm not too sure, but for the week or two i've had em so far so quiet.) here is the amzn link http://www.amazon.com/Nzxt-200mm-37-25-Bearing-FN-200RB/dp/B0039825M6/ref=sr_1_1?ie=UTF8&qid=1392506806&sr=8-1&keywords=nzxt+fn-200