A 140mm fan is the easy upgrade for a quiet PC: bigger blades, lower speed, same air. But when you compare the figures makers print, you find each one quoted at a different speed. Noctua prints 11.4 dB(A) for one fan and 24.8 dB(A) for its sibling, and the only real difference is that one spins at 800 RPM and the other at 1500.
So this guide does one thing the broader PC case fan guide does not: it sorts every 140mm figure we could confirm by the speed it was stated at, and ranks fans only against others at the same speed. We read the makers' own pages and infosheets for Noctua, Scythe, Thermalright, Lian Li, ARCTIC, Fractal Design and Phanteks, and quote airflow and static pressure at the same speed as the noise figure wherever the maker gives them.
Our picks are listed above, with full specifications for each.
Every figure on this page is a manufacturer's dB(A) for a bare fan in free air. None of the makers names a measuring distance or a test standard, which is why we never set one brand's figure against another's unless both were stated at the same speed. Our explainer on why decibel ratings rarely compare across brands covers the wider problem.
Makers state speed in three ways, and we treat each one carefully:
- A single speed. Noctua prints a table with the speed, airflow, noise and pressure in the same column, once at full speed and again with its Low-Noise Adaptor (L.N.A.) fitted. Both columns are usable, because each names its speed.
- A maximum. Thermalright marks every row "(MAX)", including the rated speed. Lian Li prints "dB(A) Max" next to a speed range ending at 1600 RPM. We read these as the figure at the top speed.
- A range with both ends. Scythe prints "4.19 ~ 19.4 dBA / 16.8 ~ 67.2 CFM" across "300 ± 200 ～ 1200 rpm", which gives the figure at both ends of the speed range.
Fractal Design and Phanteks print one noise figure beside a speed range without saying which speed it belongs to, and ARCTIC prints a Sone value with no speed at all. Those fans are listed below the picks but not ranked.
At 800 RPM
Only Noctua publishes 140mm figures this slow, so this group is one maker's fans, but it is the group that matters most for a PC that sits on your desk all day.
- NF-A14x25 G2 LS-PWM: 11.4 dB(A) at 800 RPM, 81.6 m3/h, 0.71 mmH2O.
- NF-A14 ULN: 11.9 dB(A) at 800 RPM, 79.8 m3/h, 0.69 mmH2O.
The two are close, and the newer G2 wins on all three numbers. It also keeps 4-pin PWM, while the ULN is a 3-pin fan whose speed is set by its adaptor. Both drop further with the adaptor fitted, but to different speeds, 600 RPM on the G2 and 650 RPM on the ULN, so those two figures, 8.6 and 9.1 dB(A), are not a matched pair. For every other Noctua 140mm figure, see our Noctua fan decibels page, which lists the full range by condition.
At 1200 RPM
This is the most useful group, because three fans from two makers are stated at exactly 1200 RPM:
- Noctua NF-A14 PWM with the L.N.A.: 19.2 dB(A), 115.5 m3/h, 1.51 mmH2O.
- Scythe Kaze Flex 140 Square PWM 1200rpm, at its top speed: 19.4 dBA, 67.2 CFM, 1.25 mmH2O.
- Noctua NF-P14s redux-1200 PWM, at its top speed: 19.6 dB(A), 110.3 m3/h, 1.29 mmH2O.
The spread is 0.4 dB, from fans measured under conditions no maker states, so at this speed the choice comes down to everything else. The NF-A14 PWM keeps 300 RPM of headroom for a hot day, because 1200 RPM is only its adaptor setting. The Scythe gives you a published low end, 4.19 dBA at the bottom of its range, and Scythe is the only maker here that prints one. The redux is the plain option: Noctua's six year warranty, and nothing in the box except the fan and four screws.
At 1500 RPM
Four 140 x 140 x 25 mm fans list a figure at 1500 RPM:
- Noctua NF-A14 PWM: 24.6 dB(A), 140.2 m3/h, 2.08 mmH2O.
- Noctua NF-A14x25 G2 PWM: 24.8 dB(A), 155.6 m3/h, 2.56 mmH2O.
- Thermalright TL-C14C: 26.4 dBA (MAX), 75.8 CFM, 1.93 mm H2O.
- Thermalright TL-B14: 27.6 dBA (MAX), 82.5 CFM, 2.35 mm H2O.
The two Noctua fans are 0.2 dB apart, and the G2 buys more airflow and pressure for it; Noctua ships it with an anti-vibration gasket pre-installed "to create a tighter seal on radiators". The Thermalright fans are 1.8 and 3.0 dB above the NF-A14 PWM at the same speed. Noctua quotes airflow in m3/h and Thermalright in CFM, so set each fan's airflow beside its own sibling rather than across brands.
Thermalright makes two more 140mm fans at 1500 RPM that do not fit the 25 mm square group: the TL-C14, 26.6 dBA in a 26 mm frame, and the TL-D14, 25.6 dBA in a 140 x 152 x 27 mm frame. Check your mounts before you count either one.
At 1600 and 1800 RPM
Lian Li rates its 25 mm 140mm fans at 1600 RPM, and they line up neatly:
- UNI FAN AL140 V2: 26.8 dB(A) Max, 81.6 CFM, 2.80 mmH2O.
- UNI FAN SL Infinity 140: 28 dB(A) Max, 72.7 CFM, 2.88 mmH2O, in a 140 x 142 x 25 mm frame.
- UNI FAN SL140 V2: 29 dB(A) Max, 77.6 CFM, 2.09 mmH2O.
The AL140 V2 has the lowest figure and the most air of the three. At 1800 RPM, Scythe's round Kaze Flex 140 PWM lists 26.45 dBA and 100.8 CFM, and Thermalright's TL-C14X lists 30.2 dBA and 92.5 CFM in a 26 mm frame. The Scythe mounts only on 120mm holes, which Scythe itself points out.
Slim 140mm fans
Slim 140mm fans exist for low-profile coolers and cramped top panels, and only one maker we read ties a slim 140mm figure to a speed. Thermalright's TL-B14015, 15 mm thick, lists 24.6 dBA at 1600 RPM, with 62.8 CFM and 1.0 mm H2O. Its faster TL-B14015 EXTREM lists 34.2 dBA at 2600 RPM and 92.3 CFM.
The slim fan's figure is lower than the 25 mm fans at the same 1600 RPM, but it also moves less air than any of them. That is the trade the thin frame makes, and it is why we rank slim fans separately. ARCTIC's P14 Slim PWM PST is 16 mm thick, but its only noise figure is 0.3 Sone with no speed, and its product page and spec sheet disagree on its speed range, airflow and pressure.
Why a 140mm fan can turn slower for the same air
Makers that publish a 120mm and a 140mm version of the same fan show the trade in their own figures.
- Lian Li UNI FAN AL V2: the AL120 V2 lists 77.3 CFM and 28.7 dB(A) at 2000 RPM. The AL140 V2 lists 81.6 CFM and 26.8 dB(A) at 1600 RPM. More air, 400 RPM slower, and a lower figure.
- Lian Li UNI FAN SL V2: the 120 lists 64.5 CFM and 29.2 dB(A) at 2000 RPM. The 140 lists 77.6 CFM and 29 dB(A) at 1600 RPM.
- Noctua: the 120mm NF-A12x25 G2 PWM lists 107.3 m3/h and 22.5 dB(A) at 1800 RPM. The 140mm NF-A14 PWM, with its adaptor, lists 115.5 m3/h and 19.2 dB(A) at 1200 RPM.
The larger blades move more air on each turn, so the fan can spin slower for the same flow, and slower is quieter. But the makers' figures also show it is not automatic. Thermalright's 120mm TL-C12C lists 25.6 dBA at 1550 RPM with 66.17 CFM; its 140mm TL-C14C lists 26.4 dBA at 1500 RPM with 75.8 CFM. The 140mm fan moves more air at a slightly lower speed, but its figure is higher. The gain comes from running the larger fan slower, not from the size alone. Lian Li's 120mm AL and SL fans are also 28 mm thick against 25 mm for the 140s, so these are the makers' own pairings, not identical frames.
What the numbers mean at your desk
Every 10 dB is roughly a doubling of how loud something sounds, so the 13 dB between the NF-A14x25 G2 LS-PWM at 800 RPM and the full-speed G2 at 1500 RPM is more than a doubling. Against that, the 0.4 dB spread at 1200 RPM is small. On the makers' own figures, the speed you run a fan at moves its figure far more than the choice between brands at the same speed.
A quiet home office has little else running, so a PC's fans are often the one steady sound in the room, and several of them add up. Our quiet home office explainer covers the other sources, and our decibel chart sets these figures beside everyday sounds. If you are choosing the case at the same time, our PC case guide shows which cases ship with 140mm fans, and our CPU cooler guide covers the 140mm fans on tower coolers.
Prices on the day we checked
Only two makers here show a US price. Noctua's website has no prices; its product pages send buyers to its own Amazon store, where the seller on October 6, 2026 was Noctua Cooling Solutions. There the NF-A14 PWM was $24.95, and the NF-A14x25 G2 PWM and LS-PWM were $44.95 each. ARCTIC's own US shop lists the P14 PWM PST at an MSRP of US$12.99 and the P14 Slim PWM PST at US$13.99. Scythe, Thermalright, Lian Li, Fractal Design and Phanteks show no price on their product pages and send buyers to resellers.
How we chose
We read each maker's own product page, specification table or infosheet on October 6, 2026, and recorded each 140mm fan's noise figure with the speed the maker attached to it, plus airflow and static pressure at that same speed. We grouped the fans by that speed, ranked only within a group, and kept 15 mm slim fans apart from 25 mm fans. Fans whose figure has no speed attached are listed but not ranked. be quiet! and Corsair both publish 140mm figures with a speed, but their sites blocked our requests when we went to re-check them, so we left them out rather than quote numbers we could not confirm. Where a maker prints figures in CFM and another in m3/h, we quote each in the maker's own unit.
We did not measure any of these fans. Every figure is the maker's own, for a bare fan in free air, quoted with the speed the maker states, and no maker here names a measuring distance or a test standard.
