Comment by o11c

For laptops specifically, opening them up and blowing all the dust out can be a huge difference. After that, if the fan is making noise, it's not worth attempting recovery. If attempting this, consider whether your source is cheap enough in the case your test exposes this.

Blowing the dust out does run into the problem of some laptops being designed to only open with use of a chainsaw. I've ruined a couple laptops that way.