Dust builds up underneath fans and creates a blanket causing your system to heat up which in turn can cause damage to your cpu as well as other components and ultimately may overheat them to the point where they do not work anymore. Some manufactures actually have sensors that will shut down your system.
Tip: Note dust that builds up in your desktop or laptop will lead to overheating and potential electrical shorts. This has caused many hard drives to fail due to the fact they are not able to breath. Heat and the failure to be able to expend it. Makes it a killer to any valued computer system.
Consider the low expense of an annual professional cleaning within my services page to keep your system at the temperature it was intended to perform it’s tasks.