No problems with these fans at all on a rheostat.... at least not the 4 fans in my computer. I've had 4 of these same fans running 24/7/365 for the most part of the last five years (less at most a month when I moved or went on an extended vacation).

I can run them from 900rpm up to 2700rpm, but mostly keep them around 2100rpm. Nice and quiet and they keep my water cooling nice and stable. Blue lights are the rheostats... two fans running on each. Two pushing into the radiator and two pulling from the radiator (shown in 2nd pic). Eventually I'm going to put one of these bay fan controllers in my incubator. They have two fan controllers and two temperature sensors. It would be handy to monitor temps in the top and bottom of the incubator and control the fan from one piece of equipment.