Just checked the fans in my two S9´s and both exhaust fans are connected to the FAN5 connector. No problems at the moment with the fans ramping up and down.
Thanks man, gotta check a couple of S9's that coincidentally I was cleaning yesterday and didn't check how the fans were connected.
By the way, one of these fans is reporting >30.000RPM
http://tinypic.com/r/4g6f5e/9