My daughters MBP 2009 2,53 Mhz Duo received a new main board (It is the one with only 1 fan) . So far, everything is ok. BUT: the fan is constantly turning at max speed from the start on, instantly when I push the "ON" button... I installed macsfancontrol and it shows LOW temperatures (30-42°C) everywhere, so there is absolutely no reason for max speed at all. The problem seems to be that there is no feedback about the rpm of the fan: Macsfancontrol shows all the time ZERO rpm although always at max speed. Evidently there is NO transmission of the fan speed… and I cannot change the speed because macsfancontrol gets no feedback about the rpm of the fan…. My question (before purchasing a new fan) : Might it be a failure of the fan (rpm-sensor failure or the fan cable connector ?) or might it be more a problem of the main board? Is there anyone with experience about this problem?