i use a small air compressor. my machine is a full tower with 2X 10 inch fans on the side and 6 fans inside the case. i have to blow it out about 4 times a year or when i see dust being pushed out the vent holes on the other side of the case opposite the 10 inch fans.
i do the same thing use a small air compressor and turn it up to about 30PSI but you gotta be very careful and make sure you hold onto any fans your cleaning i made that mistake about 3 years ago