SPCR's Fan Round-Up #2: 120mm Fans

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NOCTUA NF-S12 SERIES

Ambient noise at the time of testing was 19 dBA.


The retail package comes with lots of goodies.

Fast Version: NF-S12-1200
Brand Noctua Power Rating 0.12A / 1.44W
Manufacturer ? Airflow Rating 81 m³/h (48 CFM)
Model Number NF-S12-1200 RPM Rating 1,200 RPM
Retail Availability Yes Noise Rating 17 dBA
Bearing Type SSO Bearing Header Type 3-pin
Hub Size 1.63" Starting Voltage 2.9V
Frame Size 120 x 120 x 25 mm Number of Samples 2
Voltage
Noise
RPM
CFM
Power
12V
25 dBA@1m
1250 RPM
63 CFM
1.32W
9V
21~22 dBA@1m
1020 RPM
52 CFM
1.00W
7V
~20 dBA@1m
840 RPM
42 CFM
0.79W
5V
<19 dBA@1m
640 RPM
30 CFM
0.60W
@25 CFM (4.3V)
<19 dBA@1m
570 RPM
25 CFM
0.53W
May 5, 2008
The updated airflow results here are the result of improvements in our testing procedures. They are more accurate than the original results above, but they are not directly comparable. Please compare these only with fan reviews published after May 5, 2008 — or ones that have updated results published in a box like this one.
12V
25 dBA@1m
1250 RPM
38 CFM
1.32W
9V
21~22 dBA@1m
1020 RPM
28 CFM
1.00W
7V
~20 dBA@1m
840 RPM
23 CFM
0.79W
5V
<19 dBA@1m
640 RPM
18 CFM
0.60W
@20 CFM (5.8V)
<19 dBA@1m
750 RPM
20 CFM
0.68W

Slow Version: NF-S12-800
Brand Noctua Power Rating 0.05A / 0.60W
Manufacturer ? Airflow Rating 59 m³/h (35 CFM)
Model Number NF-S12-800 RPM Rating 800 RPM
Retail Availability Yes Noise Rating 8 dBA
Bearing Type SSO Bearing Header Type 3-pin
Hub Size 1.63" Starting Voltage 3.0V
Frame Size 120 x 120 x 25 mm Number of Samples 1
Voltage
Noise
RPM
CFM
Power
12V
~20 dBA@1m
820 RPM
41 CFM
0.59W
9V
<19 dBA@1m
660 RPM
31 CFM
0.48W
7V
<19 dBA@1m
530 RPM
24 CFM
0.40W
5V
<19 dBA@1m
390 RPM
16 CFM
0.34W
@25 CFM (7.1V)
<19 dBA@1m
540 RPM
25 CFM
0.41W
May 5, 2008
The updated airflow results here are the result of improvements in our testing procedures. They are more accurate than the original results above, but they are not directly comparable. Please compare these only with fan reviews published after May 5, 2008 — or ones that have updated results published in a box like this one.
12V
~20 dBA@1m
820 RPM
22 CFM
0.59W
9V
<19 dBA@1m
660 RPM
18 CFM
0.48W
7V
<19 dBA@1m
530 RPM
12 CFM
0.40W
5V
<19 dBA@1m
390 RPM
8 CFM
0.34W
@20 CFM (10.5V)
<19 dBA@1m
750 RPM
20 CFM
0.53W

May 5, 2008
Noctua's unusual fin design did not fare well in our new, more accurate test procedure. Please evaluate the new results carefully.

Noctua's unusual NF-S12 fans have been subject to a lot of hype. People have been asking about these fans since before they were available anywhere, and their odd color, unusual blade geometry and Noctua's canny PR have all done their job to build expectations. The fact that they were developed by "the Austrian Institute for Heat-Transmission and Fan Technology" and are rated for absurdly low decibel counts probably helps as well. When reacting to hype like this, a little cynicism is definitely in order, but there is room for some optimism as well. The unique design of the fan makes it difficult to predict what it will sound like without hearing it, but one thing is clear: Noctua is doing more than just paying lip service to the concept of quiet computing. The fan is like no other on the market, which means that somebody, somewhere must have put some engineering into it. The tough question is this: Was the engineering effective?

Signs are hopeful. The retail package doesn't skimp on the kind of extras that appeal to silencers: Four firm silicone grommets for soft-mounting, and an adapter ("U.L.N.A.") with some kind of resistor or diode that can be installed to drop fan speed to approximately half of stock.

The two available models spin at 1,200 and 800 RPM, and, with the help of the U.L.N.A. adapter, that can be dropped to 600 or 500 RPM respectively. Our actual tests showed the faster fan dropping from 1,250 to 640 RPM (~4.7V), while the slower fan dropped from 820 to 550 RPM (~6.9V).


Accessories include silicone grommets, a Molex to 3-pin adapter, and U.L.N.A.: "Ultra Low Noise Adapter".

Initially, we were quite skeptical that the unusually shaped fan blades could live up to their claim to provide better than usual airflow at low speeds. A similar blade design on an 80mm Mechatronics fan ended up being significantly less efficient when we compared it to more conventional designs. Additionally, the unusually wide clearance between the blade tip and the frame — intended to reduce turbulence noise — made us wonder whether the blades had enough surface area to move a significant amount of airflow.

Happily, the numbers proved Noctua's claims correct. A close analysis of the data showed that, rotation for rotation, the Noctua fans pushed about 20% more air than the rest of the fans in the test. Even better, the Noctua fans did not lose efficiency until the rotation speed dropped to ~400 RPM, while other fans typically dropped off around ~500 RPM.

So much for airflow, but what about noise? Certainly, the Noctua fans had the advantage of spinning more slowly to produce the same airflow, but we've long since learned not to judge noise on the basis of rotation speed alone. Luckily, the noise character seemed to consist mostly of the quiet, broadband whoosh of airflow, making it very easy to ignore. Close listening revealed a very slight buzz hidden underneath that gave the noise a slight edge that is absent in the Nexus fan. In contrast, the Nexus sounded more tonal, with more emphasis in the deeper frequencies.

Best of all, the better airflow efficiency meant that the Noctua was perceptibly quieter at equivalent airflow than the Nexus. The difference wasn't large, and at low speeds both were quiet enough to disappear entirely. Nevertheless, there was enough difference around ~40 CFM for this reviewer to give the Noctua the nod.

One final characteristic of the noise deserves some special mention. The Noctua became inaudible relatively early in the test, meaning that it was impossible to distinguish it from the background while it was running. But... the fan seemed to have a subconscious "presence" that hung over the room even when the fan was inaudible. The "presence" was noticeable as a change in the background noise when the fan was turned on or off. The change was felt more than heard; it was impossible to put a finger on just what changed, but there was no doubt that something had. In short, Noctua did a very good job of finding a noise character that blends easily into the background. The subjective "quietness" of the fan can be attributed as much to the fact that it is difficult to localize as to the amount of noise that it generates.

Noise Recordings

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