so one thing that is certain, it is not really spinning at 750k RPM. a fan usually spins at around 2000 RPM and not 3/4 of a million RPM... I don't think that is even physically possible... so it looks like your reporting software is off... i wish i knew more about this so i could help you, but not my area of expertise...
that said, have you right-clicked on it and updated the driver?