Replacing Alienware Fans + Airflow Concern

Hi fellow Aliens,

I have a question. After performing autopsy on an Aurora R4, I decided to replace its aging fans.

My questions are:

1. Is it necessary to use fans with same airflow? E.g. replacing 180 cfm with a slower one.

2. I plan to use air cooler and how important is the main 120 mm fan?

3. Is it necessary to have one 180 cfm fan?

I have opted not to use liquid cooler and I am aiming at getting Noctua fans.

Why I am asking this is because, one of the HDD or near MIO fan is a 180 cfm fan with 92 mm size. Unfortunately, Noctua only has 120 mm fan whose airflow is 180 cfm. The problem is, the 180 cfm Noctua fan sounds more like a turbine than a PC fan.

I am planning to transfer the 180 cfm power to the 120 mm fan while replacing the original 92 mm fan with a slower one.

Is keeping at least one 180 cfm fan is necessary?

Thank you