Case fan ducting can improve the efficiency of your case fans, for example,
if you have a 120 intake at the front of your case, you could direct the airflow
up towards the CPU area. See the diagrams below for some ideas.
120mm fan ducted upwards towards CPU
80mm fan in drive bays ducted down towards CPU
Rear fan ducted to blow air directly into the CPU
heatsink
Case fan ducts can be made from many things, you can roll up cardboard or acetate
sheet, but for 80mm ducts, there is a rather more substantial solution.
This can of fruit is 82mm in diameter, and fits an 80mm fan quite nicely. See
the end of the article for a list of things that are the right diameter to make
into ducts.
