The ENDORFY Fluctus 140 PWM is only 14 cm tall but handles keeping most CPUs cool with ease. It never loses its cool when dealing with densely finned radiators in liquid cooling systems as well as chassis with dust filters - some say it also keeps tired feet cool, but Endorfy haven't tried that. Yet. This fan with an optional semi passive mode fits into most cases. And it's easy to install as well - they have prepared a simple manual and haven't hesitated to use provide it for you.