Please refer to the dedicated test setup page as it applies to this review as well and I did not want to go over it separately to save on review space.
CORSAIR rates the RPM range of the iCUE LINK QX120 RGB as 400 to 2400 RPM. Of course there will be variations between samples, and airflow resistances will play a big role, too. The provided samples went from an average 2416 RPM at 100% PWM down to 482 RPM at 20%, following which the fans hit zero RPM mode and turn off. This is great for anyone wanting a quiet system and the fans reliably turn on and off too. The end result is a large active control range of 20-100% with a zero RPM mode and the RPM numbers themselves also fall well within rated specs. The overall RPM range is more than long enough for PC cooling use and the RPM response curve is very linear too, which makes it easy to set custom fan control curves. I was also very impressed with the minimal sample variation, especially since we have a relatively large sample set. Context is needed to talk more about the fan's relative performance and noise, so I have comparison charts below for some fans tested at set RPM values, or as near as they can get to those.
The charts above help put the CORSAIR iCUE LINK QX120 RGB fan in better context with the chosen RPM values reflecting usage scenarios most popular with watercooling, although some fans go higher as is the case here. 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. Note that these are average values for all samples of each fan and do not reflect any sample variation, and I also suggest looking at RGB fans separately from the others given they tend to sacrifice some performance by having LEDs take up space where longer rotor blades could have been pushing more air through. It would be fair to say these are not performance-optimized fans given the low airflow. At the same time, this also means there is less airflow noise too and the good news is I observed absolutely no bearing noise at lower fan speeds. There's a sweet spot around 1250-1500 RPM too but otherwise this is a fan to set a custom fan curve and make use of the longer RPM range on offer if you want to get more performance out of them.
Instead of having CFM/dBA charts that can potentially be taken for more than they really offer, I am going to show three other fans as a comparison for further context. These include the subject of this review—the CORSAIR iCUE LINK QX120 RGB—in addition to three other RGB fans from other mainstream competitors in the form of the be quiet! Light Wings 120 mm, the LIAN LI UNI FAN SL INFINITY 120, and the Thermaltake SWAFAN 12 RGB. There are newer RGB fans on the market too although none I've tested recently really go as far down the RGB rabbit hole as these four. Overall we can see there's not a lot differentiating these fans from a performance/noise basis although the iCUE Link QX120 RGB seems to fare worse from a performance/noise basis the faster the fans spin. This is a fan to get for features such as the LED lighting and the temperature sensor in addition to the iCUE Link ecosystem support, not for pure performance by any means.