One of my case fans is making a crackling sound

[u/Octatwo]

One of my case fans seems to be on its last legs as it has started making a crackling sound when running above 40% speed. Should I replace it immediately or keep it below 40%, or does the crackling not matter? I bought the fan for like 5 euros 5 years ago. Nothing is touching the fan.

[u/bullet_zing]

Its bearings are likely worn out. I'd replace it.