>>712527158You just use a can of air to blow all the dust out of the fans and other pieces twice a year. Also clean the filters in your case with an old toothbrush.
The only thing of note is to use a pencil or something to make sure the fans don't spin while spraying on them. And don't use vacuum cleaners due to static buildup.
You don't need to replace thermal paste unless you did a shit job at installing it in the first place.