Question Fans airflow

Dec 5, 2019
Does the rear and 2 top fans have to match to the 3 fans that comes with the sase?

For example: i own a case with 3, 120mm fans.
Do i have to buy the rest of the fans the same 120mm size? Or i can go with 140mm for the top of the AIO cooler, and 120mm on the rear.

Please i need a clear answer, don't wanna mess up with my case airflow.
Last edited:


Jun 22, 2019
It depends on what case you have and what you can fit in it. In principle you can use whatever size and make of fan you want, with or without lights......even mix & match.

The one point is if you are using a controller or MoBo with a splitter is the voltage of the fans 12v or 5v, that you should not mix. The other thing to be aware is of fans that have 4 or 3 pins for controling their speed.

Other than that it's what you like and can afford.

What is the make/model of your case?
What is installed inside that you need to cool?
Normally, a case with two front 120mm intakes and a 120mm rear exhaust will give you decent cooling.

A case will have provision for certain size fans in different locations.
Sometimes a location will have mounts for several different sized fans.
Commonly 120mm or 140mm.
On occasion 80, 92, 180 or 200mm fans.

A fan will be connected to power in a couple of different ways.
4 pin molex connectors to the psu will always run at full speed.
Fans connected to the motherboard will be 3 pin which are voltage adjusted or pwm 4 pins which are adjusted by timing of pulsed.

Then there is the question of RGB "bling".

My guess is that you need to do nothing.
Dec 5, 2019
Dude im building a 2,000$ pc but thx for the info,
Its a corsair build with corsaid obsidion se rgb that comes with 3LL 120mm fans. Now for the other fans that i want are 2 aio fans on top and one on rear, both corsairs. I heard the 140 mm are less noisy because they dont have to spin as fast as the 120s to get the same cooling
But in the same note i dont wanna create imbalance between the 3 front intake 120mm fans and the other 3 exhaust if they will be 140mm
So how is that gonna effect the airflow if intakes are 120 and outakes are 140