Noctua NF-S12B FLX Cooling Fan Review



One of the quietest fans i have used so far.


Ultra quiet at full speed and has adapters to adjust speed.


None at all.

Everyone knows that you need to keep your computer cool at all times to get the most out of it. The most important of all is keeping the CPU coolest–especially if you overclocked it. You also want to keep the noise level to the minimum–nobody wants an airplane to take off when you turn the computer on.

The Noctua NF-S12B FLX cooling fan will keep your computer cool and the noise down. You can use it to cool your CPU or your case; it’s up to you. While it may not be the best fan for cooling your CPU, that’s exactly what I did to see if my CPU stays cool or not. I was also in great need to reduce the noise from all the fans in my Azza Helios 910R case. So let’s see how this one does.


The NF-S12B FLX has is a 120mm cooling fan with highly optimized beveled blades featuring smooth commutation drive 2 (SCD2) technology. Like other Noctua fans, this one is also designed with noise control in mind. This is the same size fan that came with the Spire TherMax II CPU cooler but a lot quieter. The Spire TherMax II fan spins at a maximum speed of 2200 rpm–that is fast but also loud. This fan also came with three adapters to control the speed and noise levels with just like the NF-P14 FLX. I installed it on the TherMax II CPU cooler to see how it performs compared to the original that came with the cooler. This cooling fan uses SSO bearing for long life and virtually no noise while spinning. The fan blades are uniquely engineered for the best and the quietest possible performance.


In order to test this Noctua NF-S12B FLX, I have installed it on the Spire TherMax II CPU cooler to see if can keep the CPU as cool as the stock Spire fan and reduce the noise or not. This testing will only test the temperatures and not the noise levels as I don’t have the proper equipment to test it. So first I will take temperature readings with the stock fan at idle for an hour and then I will use CPU Burn-in v1.01 to load the CPU to 100% and then record the temperature. I will repeat the tests after I replace the stock fan with the NF-S12B FLX. By the way, I will use Speed Fan v4.40 to monitor the temperatures.

So it turns out that the stock Spire fan spins faster and is much louder than the NF-S12B FLX, therefore it might have better airflow. But the NF-S12B is much much quieter. So at idle, the stock fan kept the CPU temperature at around 32oC but the NF-S12B kept it at 33oC. At 100% load, the stock fan kept the temperature at around 47oC and the NF-S12B kept it at around 49oC. So even though, the NF-S12B didn’t keep the CPU cooler, it did however keep the noise level to the minimum. After installing the NFS12B FLX and the NF-P14 FLX cooling fans in my Azza Helios 910R case, I have been able to get the noise that is equivalent to an airliner taking off to whisper quiet. I don’t wake up my wife in the next room when I turn on the computer anymore. That is a good thing!


I am very much pleased with the performance and noise reduction that this cooling fan is capable of. While I would prefer a better cooler, I still am not complaining. Now, if the fan was a little faster than 1200 rpm than I wouldn’t have any issues. Just like the Noctua NF-P14 FLX, this NF-S12B is also one of the quietest fans I have ever used. The different speed adapters are nice, but you really don’t need them because even at full speed, the fan is ultra-quiet. They are only about $20 online, so there is nothing to lose here. I would highly recommend this fan looking for good cooling with excellent noise reduction.


BearingSSO Bearing
Blade GeometryNF-S12B blade design with BBT
Rotational Speeds1200 RPM
900 RPM (with L.N.A.)
600 RPM (with U.L.N.A.)
Airflow100.6 m³/h
75.8 m³/h (with L.N.A.)
49.2 m³/h (with U.L.N.A.)
Acoustical Noise18.1 dBA
10.6 dBA (with L.N.A.)
6.2 dbA (with U.L.N.A.)
Static Pressure1.31 mm H²O
0.76 mm H²O (with L.N.A.)
0.34 mm H²O (with U.L.N.A.)
Inpput Power1.2 watts
0.1 amps
12 volts
MTBF> 150,000 h
Scope of DeliveryUltra-Low-Noise-Adapter (U.L.N.A.)
Low-Noise-Adapter (L.N.A.)
4 x Vibration compensators
3:4-pin adaptor
4 fan screws
Size120 x 120 x 25 mm
Warranty6 years