打算買 iCute 金剛 5G case b/c it has 3 built in fans with temp/fan indicators.

12cm -Rear Fan, air out
Rated speed: 1200 RPM ±10%
Maximum air flow:47CFM
Acoustic sound level:21 dBA

14cm-Front Fan, air in
Rated speed: 1200 RPM ±10%
Maximum air flow:48.58CFM
Acoustic sound level:23.91 dBA

5G-side panel 25cm fan, air in
Rated speed: 700 RPM ±10%
Maximum air flow:80.97CFM
Acoustic sound level:14.9 dBA

Q1: air in = 48 + 81 = 129CFM. air out = 47CFM.
出風量約只有進風量的1/3, 會有何不良結果嗎? 那2/3風量跑哪?
進風量 > 出風量比較好 or 相反比較好?
Q2: 一般而言, fan越大, 噪音越小. why front 14cm fan比12cm rear fan吵?
Q3: 總噪音 = 15 + 24 + 21 = 60dB? or just loudest 24dB?