Rgb aio cooler

Cfm isn't exactly a good measure of performance in a fan. Fans have 2 measurements and come in 3 varieties.
1. There's high cfm fans that have blades designed to move a lot of air but at a much reduced static pressure. These make excellent case fans when there's little to no obstruction. The older Noctua NF-S12 being a good example.
2. There's high static pressure fans that don't move much air, but what they do move will go through most any obstacles such as high fin count, thicker radiators. The Noctua NF-F12 is a good example.
3. There's combo designs aplenty. These have blades designed to somewhat balance the static pressure with cfm. Some designs have slightly more cfm than sp, some have higher sp than cfm. The Noctua NF-P12 being one. These are more all purpose fans, good for any application, excelling in none.

But all that is balanced out by other factors. Two exactly the same fans can have different abilities, depending on rotational speeds. At 900rpm you might have decent sp but mediocre cfm and have a quiet fan, but bump that to 2000rpm and you get good sp, much higher cfm, but the fan is abysmally noisy.

You also have to consider restrictions vrs dissipated ability. When a rad fin is heated up by the coolant, it's going to take a certain amount of airflow to transfer that heat effectively. After that point of best transfer, you aren't doing as much so high airflow doesn't mean better performance, just means higher airflow. But fins are packed together sorta tight, quite restrictive on airflow, and require a certain amount of static pressure to force the air between them. So a high static fan is preferable, but it's still needing to move a certain amount of air or theres not enough flow to be affective.

After all that, the end result is just because a fan can move more air at high speeds than another fan at lower speeds can, doesn't mean it's a better fan or will be more affective.

For example, some Corsair radiator fans move a ton of air and run 2400-2800rpm and scream at you they are so loud. The fans on my nzxt Kraken X61 average 450-600rpm, are dead silent and are effective enough to keep my i7-3770K at 4.9GHz using Prime95 v26.6 small fft at 70°C on silent mode.
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