The following system was used to test the fans:
– Processor: Intel i9 9900K @ 5GHz
– Motherboard: ASRock Z390 Phantom Gaming X
– RAM: GOODRAM IRDM PRO 16GB DDR4 @ 3600MHz
– GPU: MSI GeForce RTX 2070 Super Gaming X Trio
– SSD: Crucial P5 500GB
– HDD: GOODRAM IRDM 1TB SSD
– CPU Cooler: SilverStone Permafrost PF240W-ARGB
– PSU: Seasonic Snow Silent 750W Platinum
– Case: be quiet! Silent Base 802 White
– Thermal compound: Noctua NT-H2
The testing of all fans is done with the i9 9900K CPU at maximum load with Intel Burn Test V2. All system fans and the tested fans are turned to their maximum speeds while the PC case has both side panels closed.
The 120mm fans has been tested using a 240mm CPU liquid cooler, the SilverStone Permafrost PF240W-ARGB at max. RPM.
The 140mm fans has been tested using a 280mm CPU liquid cooler, the NZXT Kraken X61 at max. RPM.
120mm Fan Performance
The noise level was measured at three different distances from the fans (10cm, 20cm, 30cm.) the noise was measured with a margin of error of ± 5 db.
The Noctua NF-A12X25 LS-PWM was designed to be used on the Noctua NH-P1 passive CPU cooler. However, this fan can be used as a case or heatsink fan with ease, as it features the same functionality and the bearing system as the rest of the NF-A12X25 series.
However, this fan will not be as good as the regular NF-A12X25 fans, it can’t be as it spins at a lower speed. If you want a NF-A12X25 fan that is quiet then this mode is for you, however, if you want a fan that will deliver a good static pressure and airflow then you might as well get the regular NF-A12X25.
The reduced performance when compared with the regular NF-A12X25-PWM is justified by what can only be called, “the quietest fan I have ever reviewed”. Not only that but this fan still generated a decent amount of static pressure to make it worth using on a radiator or a heatsink. However, the low-speed operation means that this fan should not be used while overclocking your CPU, as no matter how much technology and engineering a fan can have, it can’t break the laws of physics and thermodynamics.
In conclusion, the Noctua NF-A12X25 LS-PWM is one of the quietest fans I’ve ever reviewed. This is due to its low-speed operation and the SSO2 bearing system. However, this fan will never be a better alternative than the regular Noctua NF-A12X25 fans, as it cannot perform better or even at the same level. What this fan does well is be silent and deliver an adequate performance, nothing more and nothing less.