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.
yeah, that's the one phil found and many people were using.
the connector is NOT PWM, though, so you would have to cut it off, then cut off the default fan connector and splice it on a new fan wires.