Clean the radiator and ports.
Clean up the dust on the heat sink with a toothbrush first, and remember that the ports are the same, so as to be refreshing!
Run by fan type
If you feel that you need more in-depth "treatment", you have to operate according to the type of fans. First uncover the trademark paper on the top of the fan to see if there are any holes or screws.
Dropping oil
If there are screws, after unscrewing, drip high-speed mechanical oil (or sewing machine oil) into the fan shaft. If there are no screws, try to pry the fan away from the bearing with two thin iron bars and drip oil.
Come on from the small hole
If there is a small hole in the top, add oil from the small hole, and then seal the top with transparent tape to prevent dust.
Hard trick: drill the top of the fan.
For those fans that are hard to disassemble without holes, we have to do something hard: drill the plastic shell near the shaft at the top of the fan with hard objects such as awls and scissors tips (remember to be careful), and then drip oil.