Chassis ventilation, what's the ideal fan layout?

Question

Iron

Help me figure out the ventilation in the case. Fans: front and rear for blowing in and blowing out, respectively, of course, we don’t touch it. The bottom line is that after replacing the front fan, 2 120m fans remain on hand. And then there is the question of where to put them. There are 2 seats on the side cover, and 2 on top. The system is not very hot, but the temperatures in my area are high for PCs. Where to put these 2 fans? You can 2 on the top of the case, you can 2 on the side cover, or 1 each on the top and on the cover. But in which case will ventilation be better? I personally do not know, and I ask for help from you. It may be useful information, but there are 2 nuances for the front and rear fans. The front one will be replaced with a more powerful one with strong airflow and high revs, and the rear one will be the usual 120x from the factory. He leans against the wall.
PS from the side, the distance from the wall to the "window" of the case (with holes for fans) is 4-5 cm. For blowing from above - more than 20.

Answer 1

The fan has the characteristic "Air flow" can be indicated in CFM (cubic feet per minute, CFM) - cubic feet per minute, in short - in some "parrots".
See how many "parrots" your Front one blows in - - more powerful with strong airflow, how much it sucks out a regular 120x standing from the factory. For normal operation, how much is blown in - about the same amount should be blown out.
Put one on top for blowing out, the second one on the side for blowing in or on top for blowing out, depending on the "parrots"
PS If there are no cats and small children in the apartment, just remove the side cover and turn off all the fans: the effect will be about the same ...

Answer 2

ну если передний вентилятор самый мощный , то нужен фильтр , что комп не превратился в пылесос , а 2 освободившиеся на верх на выдув