In some cases you have some flexibility when choosing fan sizes.
Most quiet case fans 120mm.
Rosewill rgbf 17002 rgb case fan set 120mm case fans with 17 key remote control 8 port rgb fan hub 2 x 120 mm rgb case fans set ultra quiet pc fan set 2 pack type.
140mm fans generally have the same mounting holes as 120mm fans for example.
But as a general rule larger fans are quieter move.
If you ve got a big case and need to move as much air as possible through it then you ll probably need to be looking at the monstrous megaflow 200 which is the best 200mm case fan for keeping big cases cool.
While 120mm case fans are pretty much the standard these days there are other options both smaller and larger.
The big advantage of a 120mm fan is that because its blades are larger than most of the other common fan sizes the fan does not have to spin as quickly in order to produce a given amount of airflow.
Here we have one of the most silent 120mm case fans which is the 800rpm version of scythe kaze flex 120 case fan.
Case fan bearing type.
120mm fans have enjoyed a massive surge in popularity in recent times with many case manufacturers now including 120mm fan cutouts as standard.
Long life bearing 30 000hrs 100 degree f.