Looking for a little help here from someone who may know... I have a Fractal Design R5 with the stock fans running, as well as some type of cooler master cpu cooler with a fan I forget off the top of my head. I have decided recently to try and lower the noise level of my computer a bit so after doing some researching it seems the Noctua fans are pretty highly rated for decent airflow and noise. My question is, there seem to be many different type of 140mm Noctua fan models. I need help on figuring out which ones to get. Which are better? Theres like NF-A14 PWM, NF-P14 Flex, etc, etc Someone narrow down which are the best to get. I am looking for quiet but good airflow. From what I read, the NF-A14 Flex is good for case fans and the PWM is for headsink fans? I will need two 140mm fans and one 120mm fan. Thanks.