When choosing a PC case or heatsink , including liquid cooling , one of the crucial factors is the size of the fans. Generally, the boxes have fan holes limited to one size, although there are many that allow both 120 and 140 mm, but in the case of liquid cooling, it goes further because the radiators have certain sizes (120/140 mm, 240 / 280 mm, etc.). So is it better to go for 120 or 140mm fans ?
It is popular knowledge that, all other things being equal, 140mm fans, having a larger surface area, are able to move more air volume, or even move it, but rotating more slowly and therefore generating less noise. However, the reality can be quite different, and it is often a difficult decision to make.
120 or 140mm fans, which option is better?
The answer is, as always, that it depends on what you need. Take for example two models from the popular manufacturer Noctua, within its IndustrialPPC range: the Noctua NF-A14 3000 PWM and the Noctua NF-F12 3000 PWM, two fans that rotate at the same maximum speed and that, according to their technical characteristics, the The biggest difference lies only in its size.
The 140mm model is capable of rotating at up to 3,000 RPM, speed at which it moves 269.3 m³ / h of air emitting 41.3 dBA of noise. For its part, the 120mm model also rotates at 3000 RPM but moves an air flow of 186.7 m³ / h emitting 43.5 dBA of noise.
It is obvious that with equal conditions and speed, the 140mm fan is not only capable of moving a much higher air flow than the 120mm model, but it also does so by emitting a lower noise level; therefore, the bottom line here is that other things being equal , 140mm fans perform better than 120mm fans .
Not all fans are created equal, nor is their purpose
Now, you should bear in mind that this comparison that we have made is on equal terms, but the reality is that not all models are the same nor have they been designed for the same purpose.
Therefore, when designing the air flow of your box or the cooling of your heatsink you should always take into account what model of fan you want to use and what its characteristics are, because there are 120 mm fans that deliver better performance in radiators than other 140 mm, for example.
The recommendation here is that you always look at the characteristics of the fan and compare, taking into account what interests you the most but taking into account that in general, a 140 mm fan will almost always deliver better performance and causing lower noise level than 120mm fans. The bigger the fan, the normal it is to have better performance.
So are 140mm fans better?
As we have said, as a general rule it is almost always like this. By having a larger surface area, they are able to move a greater air flow at the same speed, or the same air flow as those of 120 mm, but operating slower and, therefore, generating less noise.
Therefore when choosing a case for your PC, a heatsink for the processor or a liquid cooling radiator, you must take into account that the larger the size of your fans, the better performance and lower noise level you will have. . Thus, a box that supports 140 mm fans in the front, roof and rear will always be better, and in the same way, a liquid cooling system with a 280 mm radiator will give you better performance than another with a 240 mm radiator.
In fact, and leaving aside the 120 and 140 mm fans, the boxes that have 200 mm fans on the front are usually boxes with an excellent internal air flow and therefore thermal performance, and they are also much more silent. As a general rule, a box with a single 200mm fan on the front has better thermal performance than one with two 120mm fans in the same position, and it will also be quieter.
