Question about a weird laptop fan noise I heard in a repair last Friday

I was fixing a Dell Inspiron for a client in Austin and the fan made this high pitched whine, like a tiny whistle. It only happened when the CPU hit 60 degrees, not before. I cleaned the heatsink and replaced the thermal paste but the sound came back after 20 minutes. The fan itself spins fine, no wobble. Has anyone else run into a fan that whines only at certain temps? I'm thinking maybe the bearing is going but I want to be sure before I order a new one.

3 comments

3 Comments

lisab431mo ago

That specific whistle at a certain temp is such a weird one. I've seen fans with a bad bearing make noise at all speeds, but that temp trigger makes me wonder about the fan's control circuit. Could it be the motor straining at that exact voltage step?

mia5921mo ago

Wait, it only happens at exactly 60 degrees? That's wild.

wendyc5326d ago

Yeah, totally! I had a laptop that did the same thing, but at around 70 degrees. It would get this high pitched whine just as the fans kicked into a higher gear. Drove me nuts until I finally figured out the pattern. It's gotta be something with the power switching at those specific points, like lisab43 said. Something in the circuit just doesn't like that exact speed.