Please refer to the dedicated test setup page here
as it applies to this review as well and I did not want to go over it separately again.
Let's remind ourselves that the fan is rated for 350-2200 RPM (+/- 10%). All three fans hit an average 2168 RPM at 100% PWM duty cycle and went down to an average 324 RPM at 27% PWM duty cycle before turning off completely. This is no bug, and EKWB calls it the 0dB start-stop functionality. These fans will turn off at lower duty cycles thus, with the exact number depending on the specific PWM controller and header used. This means you get complete silence from these fans, and the graph above goes to 19 dBA because that is the floor's ambient in my anechoic chamber used for testing. In order to turn them back up, increase the PWM duty cycle percentage, but note that this means startup boost for current draw is now added, so if you plan on using this feature, account for the worst case power-draw scenario or use a PWM-powered splitter.
Other than that, these four fans had an average response across a long 27%-100% duty cycle, one close enough to the rated speed range to where I have no complaints. The standard deviation between the fan samples is minimal too, so if these four are anything to go by, all the better. The RPM response is also very linear, which is good to see. Alongside it, I have mapped the RPM response curves for this fan vs. the older EK-Vardar F4-120ER as well as the even older EK-Vardar F4-120 fans, and we see a consistent improvement with each release to where we now have both an extended range of control and EKWB's zero-RPM mode.
Context is needed to talk more about the fan's performance and noise, so I have below comparison charts for some fans tested so far at set RPM values (or as near as they can get to those).
I have included fans in charts where the rated RPM is within 50 RPM of the chart cutoff point, which means that some fans are in specific charts only if their rated speed is over 50 RPM off from a threshold value (Corsair SP120 RGB, for example) or they simply do not slow down enough (NB-eLoop B12-4, for example). Similarly, the specific RPM values chosen reflect usage scenarios most popular with watercooling, even though some fans (the EK-Vardar EVO 120ER, for instance) go higher. The charts are to be considered for comparison within this result set only and are not to be compared with results from another test elsewhere owing to different testing conditions.
EKWB promised a fan that is all about performance as a radiator fan, and they have delivered big time. Indeed, we see that the predecessor EK-Vardar F4-120ER was already a very good fan here, but the addition of the hydro-dynamic bearing helps at lower fan speeds by keeping overall fan noise low. As the RPM increases, airflow noise takes over, and with a performance-tuned fan such as this, we consistently have the highest airflow numbers through the radiator along with high, but not the highest, noise levels to go with it.