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FAN TEST RESULTS
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We've seen the 12cm NF-P12 before, on the Noctua NH-U12P. The 14cm NF-P14 is
new to us. It is similar in design to the NF-P12, except for size: To maximize
pressure, the nine fan blades have less curvature than typical fans. There is
more of a gap between the blades than in the 12cm model. The "vortex-control
notches," which apparently reduce turbulence and spread the noise generated
from the interaction between the strust and the fan blades over a wider frequency
range, making for a more pleasant sounding fan. The 14cm fan's frame is fairly
minimal, allowing for the same hole mounting pattern as a standard 12cm fan.
Both fans have good strut geometry; the trailing edges of the blades intersect
with the struts almost perpendicularly, which in theory also helps to minimize
tonal aspect of the turbulence noise. Noctua's "self-stabilising oil-pressure"
bearing (SSO bearing) is said to surpass ball, sleeve or liquid bearings in
terms of long-term stability and quietness. More details of the fan designs
can be read on Noctua's web site.
The 14cm fan bearing looks a bit different from the 12cm fan. The bearing end
looks similar to that of the excellent Sanyo Denki San Ace fan employed in the
high end Seasonic X series and MD12 series power supplies. (See
photos on this page.) Noctua has this to say: "Both the impeller hub
and the bearing shell of the NF-P14 are metal reinforced in order to achieve
ultimate manufacturing precision, high durability and vibration-free running."
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The metal end of the fan shaft looks impressive..
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The blue marked parameters in the tables below were measured in our lab. Both
fans draw exceptionally low power.
| Brand |
Noctua |
Power Rating |
0.09A |
| Model Number |
NF-P12
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Airflow Rating |
92,3 m³/h |
| Bearing Type |
SSO
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RPM Rating |
1300 |
| Hub Size |
39.5 mm |
Noise Rating |
19.8 dBA |
| Frame Size |
120x120x25 mm |
Header Type |
3-pin |
| Weight |
170g |
Starting Voltage |
4.8V |
| Brand |
Noctua |
Power Rating |
0.10A |
| Model Number |
NF-P14
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Airflow Rating |
110,3 m³/h |
| Bearing Type |
SSO
|
RPM Rating |
1300 |
| Hub Size |
39.5 mm |
Noise Rating |
19.8 dBA |
| Frame Size |
140x140x25 mm |
Header Type |
3-pin |
| Weight |
150g |
Starting Voltage |
6.5V |
Two low noise adapters are provided, one for each of the fans. The instruction
sheet warns against running both fans off either adapter simultaneously. This
can be done with the splitter cable that's also provided.
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Ultra-Low-Noise Adaptors: The blue one has an 81 ohm resistor, while the
black one measures 50 ohms. The first brings the speed of the 12cm fan
down to ~900, and the second does the same to the 14cm fan.
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To get started with the acoustics, noise and speed tests were run on each fan.
Each fan was left mounted on the heatsink (with the other one removed) since
that's the way they would be used. The noise of both fans running together was
also measured; this is the way the heatsink is meant to be used. Note
the order of the columns in the table below: All the Sound Pressure
Level (SPL, measured in dBA at 1m distance) data is in the middle three columns
for ease of comparison.
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Noctua NH-D14 Cooler: Fan Test Results
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NF-P14 fan
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SPL, both fans
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NF-P12 fan
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V
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RPM
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SPL
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SPL
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RPM
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V
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12V
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1230
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30
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30
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24
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1285
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12V
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11V
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1130
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28
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28
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22
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1210
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11V
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10V
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1040
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25
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26
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20
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1100
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10V
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9V
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940
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22
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22
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17
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1000
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9V
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8V
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840
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19
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20
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16
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900
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8V
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7V
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720
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15
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16
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13
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800
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7V
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6.5V*
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660
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14
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14.5
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12
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680
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6V
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5V
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490
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12
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12
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11
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570
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5V
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* 6.5V is the min. start voltage of NH-P14 fan; to
get it to run at 5V, the fan must be started at a higher speed, then the
voltage reduced.
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Our SPL measurements make a mockery of Noctua's claimed 19.8 dBA at full speed (as well as the ~13 dBA claim with the ULNA). This exaggeration is especially notable when the rest of the specs are so professionally correct.
The 14cm fan is considerably louder than the 12cm model throughout the speed
range. The difference reduces as speed is reduced; by 7V, the noise level from
either fan is soft and gentle enough that the 2 dBA@1m difference is of little
importance.
Each fan has a better qualitative sound when run by itself. Both fans are fairly
smooth, but with a bit of growl and some tonality that becomes more clearly
audible as turbulence noise subsides with reduced voltage. The 14cm fan seemed
a bit smoother in this regard; despite its higher SPL, it somehow made a more
pleasant sound through much of the speed range.
Run together, the sound has more growl and turbulence, and there are some mild
intermodulation effects between the fans, which is almost unavoidable due to
their slightly different speed. At 7V, the overall SPL of the two fans together
matches the reference Nexus 120 fan at 12V. We prefer theNexus for its smoother,
less tonal sound.
At the 6.5V minimum voltage determined by the larger fan, the two fans are
very quiet together. There is considerably less tonality than at 7V.
When the low noise adapters are used as directed by Noctua, the end result
is about 22 dBA@1m, with each fan spinning around 900rpm.
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