I run a Noctua NH-D14 on my system and have a regular routine of checking and cleaning the fins and fans of it, along with checking the filters and fans built into the PC chassis. It is amazing how much dust can be gathered in a very short space of time and it is worthwhile checking things every 3-6 months.
Just be careful what you use to clean the PC components with, especially where the motherboard is concerned and don't do what a friend of mine did, which was to stick a metal pipe from his vacuum cleaner inside the PC case to suck up the dust, with the PC running! He did get a nice clean machine but at the cost of a full rebuild.