"Ignoramus5827" wrote in message
...
I have a couple of devices with very noisy and annoying fans. One is
an old laptop and another is a car inverter. In both, fans make a very
annoying, inconsistent, and rattling sound. Before taking those things
apart etc, I wanted to double check what is the typical cause of this
and how to deal with them.

i

Worn old sleeve bearings and noisy fan blade design. Replace with a nicely
designed ball bearing fan. Alluminium framed / ally bladed fans seem
quietest in my experience.