For anyone looking to put
slightly quieter fans (that still get the job done) on their S5, here's a dang good deal on a pair of Delta AFB-1212SHE. This seems to be a popular choice for reducing dBs while still keeping temps under the 60C target.
http://www.ebay.com/itm/191472588964?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITTwo fans for 20 bucks shipped. Not sure what's up with the 4-pin connecter, something looks off about it. I just placed an order and will update when they come in. Hope this helps someone.