Noctua NF-A12x15 Fan Review

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Noctua has released a new 15 mm thick fan, named the NF-A12x15. It is designed to fit in skinny places and to provide relatively high static pressure. They faced challenges getting a fan this thin. For example, “For the 12cm NF-A12x15, a steel-reinforced motor hub and brass axle mount are being used in order to assure the required stability despite the fan’s 15mm “thin profile.” Remember, Noctua guarantees their products out to six years and to make a thin fan last that long took some work. They also never made a fan this thin. As our press contact commented, “All of the new models are new form factors for us.” So let’s have a look at this, the newest entry into the slim fan derby:

Noctua NFA12x15

Introducing the Noctua NF-A12x15

Noctua says, “the NF-A12x15 is a highly optimized, premium quality quiet fan in size 120x15mm.” They go on a bit on their website but I wanted more details for you, the reader. So I asked where they think people will use this fan. What my contact said was we wanted to put the NF-A12x15:

“Basically everywhere a 25mm deep 120mm wouldn’t fit or would cause compatibility problems. One of the key examples would be low-profile down-draft CPU coolers like our own NH-L12, which will be updated with this fan later this year:

Noctua NFA12x15 & L-type heatsink

There are a lot of similar coolers from other manufacturers which also come with slim 120mm fans, so we expect that users who seek to replace these will also find the NF-A12x15 attractive. With some tower coolers, replacing a front-mounted 120x25mm fan with a 120x15mm one can help to improve RAM clearance.

With watercooling radiators, users sometimes have the issue that if they install them in the top or front of their cases with 120x25mm fans, either the radiator or fan will overhang the motherboard and possibly block some components. Using 120×15 can help here as well.

Similarly, clearance can also be increased in case fan applications or many other situations where you want to put a larger diameter, quiet fan but cannot fit 25mm thickness (think of adding a fan on a PCIe card, etc.).

Last but not least, we expect some demand from our non-PC industrial clients as well. There are a lot of applications where saving some space in order to build slimmer, more compact devices can be attractive.”

(from the product page):

  • Metal-reinforced motor hub. With many larger-diameter slim fan designs, the shorter axis and bearing lead to a reduced running stability and lifespan. The NF-A12x15 uses a metal-reinforced motor hub, a measure typically found in high-speed industrial fans, in order to guarantee Noctua’s signature stability and longevity.
  • Flow Acceleration Channels. The NF-A12x15 impeller features suction side Flow Acceleration Channels. By speeding up the airflow at the crucial outer blade regions, this measure reduces suction side flow separation and thus leads to better efficiency and lower vortex noise.
  • Noctua’s AAO frame (including Stepped Inlet Design, Inner Surface Microstructures and integrated anti-vibration pads at the corners).
  • Low-Noise Adapter [PWM and FLX fans] and Ultra-Low-Noise Adapter [FLX fan] to reduce the speeds of the fans.
  • SSO2 bearing, where the rear magnet is placed closer to the axis to provide even better stabilisation, precision and durability.
  • For the PWM fan, NE-FD1 IC to produce silent PWM fan control. It suppresses PWM switching noises and thus makes the fan quieter at low speeds.
  • Extensive cabling options. The fan’s short 20cm primary cable minimizes cable clutter in typical applications while the supplied 30cm extension provides extended reach when necessary. Both cables are fully sleeved. With the PWM version a 4-pin y-cable allows the connection of a second fan to the same PWM fan header for automatic control. With the FLX version the 3:4 pin adapter allows the connection of the fan directly to the power supply.

Noctua also advertises its six-year warranty. From personal experience and the testimony of a number of forum participants we can say that they have world-class customer service.



120x120x15 mm

Mounting hole spacing

105×105 mm


3-Pin [with FLX] or 4-Pin PWM



Blade Geometry

A-Series with Flow Acceleration Channels

Frame Technology

AAO (Advanced Acoustic Optimisation)

Rotational Speed

1850 RPM (+/- 10%)

Rotational Speed with L.N.A.

1400 RPM (+/- 10%)

Rotational Speed w/U.L.N.A.

950 RPM (+/- 10%)


94,2 m³/h* (55.4 CFM)

Airflow with L.N.A.

70,8 m³/h* (41.6 CFM)

Airflow with U.L.N.A.

46,5 m³/h* (27.3 CFM)

Min. Rotational Speed
450 RPM (PWM, +/-20%)

Acoustical Noise

23,9 dB(A)

Acoustical Noise with L.N.A.

16,8 dB(A)

Acoustical Noise with U.L.N.A.

10,2 dB(A)

Static Pressure

1,53 mm HO

Static Pressure with L.N.A.

0,9 mm HO

Static Pressure with U.L.N.A.

0,45 mm HO

Max. Input Power

1,56 W

Max. Input Current

0,13 A


12 V


> 150.000 h

Scope of Delivery

  • Low-Noise Adapter (L.N.A.) [FLX and PWM]
  • Ultra-Low-Noise Adapter (U.L.N.A.) [FLX]
  • 3:4-pin power supply adapter [FLX]
  • 4-pin y-cable [PWM]
  • 30cm extension cable
  • NA-AV3 anti-vibration mounts (4)
  • Fan screws (4)
  • Installation Manual


6 years

* -one can see the conversion factors in the link above.


First we have a look at the boxes these fans come in. The front has the marketing points along with an embossed medallion that tells you that this is a 15 mm fan. The back repeats the marketing points as text in eight languages. You can find all of the NF-A12x15 specifications there. The front covers of the boxes open out to show you diagrams of their aerodynamic features, as well as giving you a window to see part of the fan itself.

Twin Boxes - Noctua NF-A12x15

Twin Boxes

Twin Boxes - Open - Noctua NF-A12x15

Twin Boxes – Open

Inside we have the fan and its accessories snuggled in a recyclable plastic case. Here the case is laid on top of its cover – the same cover that we saw on the box in the second picture above, providing a window to glimpse the NF-A12x15.

Noctua NF-A12x15 Plastic Case

Plastic Case

The NF-A12x15 FLX comes with a number of 3-pin accessories. Here we see, lying on an open copy of the Installation Manual, an NF-A12x15 FLX, an extension cable, a package of four standard fan screws, a Molex to 3-pin adapter, four double-ended soft silicon mounts designed to attenuate any stray vibrations, an LNA (a Low Noise Adapter, RC-10) and a ULNA (an Ultra Low Noise Adapter, RC-13) — you can’t tell which is which, but I have access to the original 3968×2232-pixel picture I took, and can read the labels. One thing about the four double-ended soft silicon mounts: you can trim off the ends if you don’t use them, leaving your case looking nice from the outside.

3pin accessories Noctua NF-A12x15

3-Pin accessories

The NF-A12x15 PWM comes with various 4-pin accessories. Here you can see a four-pin Y-cable. It has the RPM-reporting line missing from one limb. This is the preferred construction since it sends a single RPM signal, thus refraining from confusing the motherboard. Next is a 4-Pin extension cable, a package of four standard fan screws, four double-ended soft silicon mounts, the fan in its shelter and a 4-Pin LNA (RC-7). Nice set. It all sits on an installation manual which is available online.

PWM Accessories Noctua NF-A12x15

PWM Accessories

Outside the sheltering case, a pair of NF-A12x15 PWM fans stand up for your inspection. These are solid fans. You can feel their solidity when you take them out and handle them.

Twin Fans Noctua NF-A12x15

Twin Fans

The next image shows the edge of the NF-A12x15 FLX is really only 15 mm thick. The edges are slotted. We have seen this before in thin fans, so the rib is there to improve stability. According to Noctua, “The slots on the outside of the frame are to make it more rigid and to make sure it doesn’t warp in the cool-off phase after injection molding.” So now we’re into manufacturing technology.

15mm thick Noctua NF-A12x15

15mm thick

A closeup of the fan shows the various features of the AAO Frame – the vibration-absorbing corners, the stepped inlets and the inner surface micro-structures. You will also notice the small distance from the end of the blade to the inner surface of the frame. Having such close tolerances requires strict attention to quality control. Most fans leave a lot more room for manufacturing variation. Finally, notice the shape of the hub – that of a short cylinder, or a built-up pancake. That is the bearing. As my Noctua contact says, “The metal reinforcements of the NF-A12x15 don’t concern the motor as such, it’s just the impeller hub that’s reinforced. You’re right that the [other OEM] uses a similar design, but so do hundreds of other high-speed fans from various manufacturers.” Further, he noted, “You need to get the tolerances down if you want to get good performance in such a dense form factor. This is one of the reasons why we went for the metal reinforced hub because it helps to keep things nice and balanced even with such small tolerances.”

Frame Closeup Noctua NF-A12x15

Frame Closeup

Noctua does not claim any special blade angle. However, I inspected several fans for blade angle. The NF-A12x15 seemed to have a similar blade angle to the NF-F12, the San Ace and the Gentle Typhoon, all seen below. They were distinctly shallower than the NF-S12A or the Slip Stream. This shallow blade angle is similar to a low gear on your bicycle or car, with the steeper blade angle being more like a high gear: those fans push air faster but have a relatively lower static pressure. However, I am still thinking about how to measure blade angle, and I’d welcome your thoughts in the comment section.

A view of the backside of the frame comes next. This side of the frame has a smooth exhaust expansion – no stepped slope here. Again you can see the inner surface micro-structures and the vibration-absorbing corners, this time with the whole shape in view. The impeller’s hub is 10 mm thick. At the hub the frame measures 4 mm thick, leaving 1 mm between the impeller and the hub, again showing good quality control. There are five struts connecting the hub to the frame, more than the normal three to four struts. This will aid in providing stability in a fan that is only 15 mm thick. Noctua’s spokesman said, “The five struts are for rigidity as well. To make it stiff enough with 4, the struts would have to me much thicker, so the overall impact on airflow would have been higher than with the 5 strut design we ended up going for.”

Exhaust Side Noctua NF-A12x15

Exhaust Side

Setup for Testing

The fans were placed in a test stand, where their free air RPM was observed and their noise was assessed. The standard proxy for what you can hear is the Sound Pressure Level (SPL), measured in decibels and given a type A weighting (dBA). A silent room is about 30 dBA.

The ambient noise for this set of testing is 31 dBA. To measure noise levels that were softer, the Sound Pressure Level (SPL) was measured 10 cm from each fan. SPL was adjusted to 1 meter by subtracting 20 dB. The sound pressure meter is a Tenma 72-942. This fan tester has a microphone which is not accurate under 30 dBA. This is the limit of all but the most expensive SPL meters. At low levels sound measurement by extrapolation is not accurate, so that sound measurements are approximate.

The airflow was assessed using a standard measure, cubic feet per minute, or CFM. The air entered a sealed 8″x8″x8″ box (200+ mm on a side) where it was allowed to mix. The air left the box through an exhaust port, where it was measured with the vane head of an Extech AN100 anemometer, averaging 10 readings per fan setting. The fans were tested in an unobstructed state, with a metal mesh dust, on a 16 frame-per-inch radiator as a proxy for heatsinks and on a 30 FPI rad.

Noctua NF-A12x15Results of Testing

There was little difference between free air and air impeded by a dust filter. As far as the NF-A12x15, the dust filter was hardly there. It turns out that this was no surprise to the folks at Noctua: “With all of the recent A-series models, we aim to have a very stable P/Q curve, so you’re right that you should see a lower drop in airflow when working against back pressure.” There being little difference between the NF-A12x15 FLX and the PWM without a LNA, the results were pooled. On the other hand, the results diverged between the PWM and FLX fans with LNA, so the averages were reported separately. All in all, you can see that the strong suit of the Noctua NF-A12x15 is quiet running.

In all three charts, fans with asterisks are slim fans.

Noctua NF-A12x15 Case Results

With the 16 FPI rad results, there was a little more separation between the obstructed vs free-path results, but they stand out from their immediate neighbors as showing dips, or reduced unobstructed airflow. This is not a bad thing, though. It shows that compared to their neighbors they have pretty good static pressure. If we put the chart in order of unobstructed airflow, these fans would show their high flow through the 16FPI rad. I put in the NF-A12x15 FLX with UNLA because it can put air through a 16 FPI heatsink. You would use it in a heatsink only if you wanted a dead-silent rig. Since you might be looking to do just that, the NF-A12x15 FLX with UNLA was included here. The results of the PWM and FLX fans were very close so they were pooled for the airflow without and with the LNA.

HSF Results Noctua NF-A12x15

Again the results of the PWM and non-PWM of the NF-A12x15 fans were very close so they were pooled for the airflow with and without the LNA. Again the fan with its ULNA was shown here because you might want a dead-silent rig.

Rad Results Noctua NF-A12x15Finally, we come to the issue of PWM control. Now, where there is a functional speed-reducing adapter we would expect the speed of the fan to be reduced at low PWM %. However, at the low end of the PWM of the Noctua NF-A12x15 PWM we get little reduction of speed, while as the PWM duty approaches and reaches 100% the speed diverges. This is exactly the way you would like a PWM fan to behave. RPM vs. PWM is graphically represented in the following chart:

RPM v PWM Noctua NF-A12x15

The one thing that we can’t measure is the nature of the sound. The NF-A12x15 is like other fans from Noctua: it does not sound as loud as it measures. The SPL meter measures the sound pressure where it is sited. But sound pressure is not what you hear. You hear noise, and you can barely hear the sound the blades make as they whirl in the air. This is a quiet fan.

Pricing and Availability

Here is the MSRP for the Noctua NF-A12x15

  • NF-A12x15 PWM: EUR 19.90 / USD 19.90
  • NF-A12x15 FLX: EUR 19.90 / USD 19.90

As of this writing the NF-A12x15 is not available on Amazon or Newegg.

Conclusions on the Noctua NF-A12x15

Static pressure readings are nice to have, but all they really do is suggest how a fan might perform when blowing through restrictive environments. What you really want to know is how well will my fan push air through my cooler (in this case, it might be a rad)? When you take out the sleeve bearing fans what is closest to this fan is the $30 Noctua NF-A14 iPPC-3000 24V. And that is comparing the NF-A12x15 to 25mm thick fans. But this is a slim fan, and the pickings for those is, well, slim. In other words, you lose nothing if you go with this fan.

The Noctua NF-A12x15 is a fine fan, never mind that it is also a slim fan. They used airflow-enhancing features, close tolerances and a good rigid frame so that it would not warp – supporting those close tolerances. Noctua has gone all-out to make this a great fan.

They have also included a number of accessories so there is little or nothing left to buy. By including a LNA, they are in essence giving you a second fan. And the FLX having a UNLA, it’s like getting a third fan. When you look at the price, you are getting a great deal in a slim fan.

Overall, Noctua has built the NF-A12x15 as a slim fan to fit in tight places where a normal fan would not go. Better, they built a slim fan that would lose nothing in comparing it to normal thickness fans. Last but certainly not least, it’s a quiet fan, quieter than its competitors.

NF-A12x15 Pros

  • Slim, only 15 mm thick
  • Very quiet
  • Surpasses surprising obstacles for such a slim fan
  • Solid construction
  • Many useful high-quality accessories included
  • Anti-vibration rubber corner pads built in
  • Both versions of the fan come with an LNA
  • The FLX has an ULNA
  • Comes with an installation manual that is also online
  • Price is reasonable

NF-A12x15 Cons

  • None

Click the stamp for an explanation of what this means.


Ed Hume (ehume)

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  1. I can't get a blinking cursor in dialog box in Chrome. Fired up firefox first time in a long time just to respond. sorry about the bbbb, don;t even know how that posted.

    The a12x15 should open up 10 more MM of space behind my fan, though I am not sure the existing restriction is impeding flow on the NF-f12.

    If I acquire it, then I have the existing NF-f12 to move to where the unacceptable 80mm Addo resides. Opening up the thin plywood to accommodate 120mm is not an issue. This is just a plywood cabinet in a caravan. The 80mm Addo fan currently pulls some air through condenser when main cabinet door is closed. I have it slowed way down with Noctua's LNA cable so I cannot hear it over the other fans usually running. Below it resides solar charge controller, inverters and chargers.

    Out of curiosity why the P12 over the F12 for the cabinet fan? Is it better with restriction behind rather than in front of the impeller?

    Thank you for the clarification of the Noctua prototype with 9 bladed GT like impeller.

    My ceiling vent currently employs a silverstone fm121 and attached to the SS fan is an Arctic f12 open case fan which counterrotates in relation to SS fm121, and acts as a feeder fan for the silverstone. These together blow through a 4 inch step down ring and into a mushroom vent There is considerable restriction in front of the fans. The SS fan's noise at max speed is greatly lessened by switching on the arctic F12 fan, and Airflow also appears to be much higher.

    Anybody else consider feeding a fan with another counterrotating fan? I tried two fans inline 10MM apart or so, which spin the same and the noise usually increases and airflow decreases, but with the counter rotating fan, noise decreases and airflow increases.

    I want to replace the SS fm121 with a Noctua 3000 rpm industrial 120mm and their speed controller to make this roof exhaust even more effective. Will likely employ the F12 as a feeder fan again as it is already there. The Noctua Ipppc3000 should be much better at forcing air through the step down ring/ mushroom vent, and use less battery power when doing so. In theory.
    I know nothing about any delay.

    The fan you saw is the prototype 12x25mm fan, like your NF-F12. However, it looks like a Gentle Typhoon. Noctua's PR guy says the hub is shaped that way because of the bearing -- all industrial fans look that way. So their 12x25mm will have 9 blades, but the current A12x15 has seven.

    Noctua also makes 80mm fans, for a drop-in replacement for your Adda.

    The review also shows the 12x15 equaling the F12 on the 16FPI CFM, but 3dB quieter.

    But for a cabinet fan I would recommend the NF-P12, but they don't make that anymore. Or I would recommend a San Ace Silent type -- 9S1212x40y, where x = S, M, F, H and y = 1,2; available from (you will have to put on your own cable ends) -- or the Gentle Typhoon -- or waiting for the prototype Noctua GT-clone when it goes into production.

    NB -- The Noctua guy says they developed the prototype fan on its own, but I note the GT has been around a while; I get the impression some key GT patents have expired or will soon expire. Expect GT clones to hit the market when the patents expire.
    Thank you for your in depth reviews eHume

    I was confused by the youtube videos showing a Noctua fan that appears to be 120MM and has 9 blades on the impeller.

    Any Idea which fan that is, or is is some unavailable prototype?

    I though perhaps they were running a ringer in their dual nf-f12 vs the single a12x15 fan test in in the video.

    I am very satisfied by the nf-f12 on my fridge condenser. The sleeve bearing fan the fridge came with has been employed elsewhere, and just recently decided it will not start on its own without a manual nudge of the blades.

    I was considering getting another Nf-F12 to install in another portion of my cabinet for the low noise and low amp draw. There currently resides an Addo 80mm fan on a noctua LNA cable to slow it sown to tolerable noise levels.

    This fan will draw some air through the fridge condenser depending on how I have the partition set up.

    Not sure the fins per inch of my condenser, but your tests show the A12x15 outperforming the nf-f12 then perhaps I can shave more time of the compressor run times and use less battery power.

    The fan on the condenser only comes on with the fridge compressor the other cabinet fan runs 24/7.

    I thought the a12x15, being thinner might allow more room near condenser to pull air, and also be able to push more air through condenser. The extra 0.08 amps is not really a concern, especially if it can further reduce compressor run times. I could then take the older NF-f12 and install it where the despised 80mm Addo fan resides and cool other electronics better and also work in conjunction with the fan on the condenser as the cabinet is pretty tight.

    I keep havnig issues with no cursor presenting itself in the reply box. This reply was delayed several hours because of it. Is it a new member delay?
    In the review there is a clear shot of the 12x15 fan -- 7 blades. It puts out 46 CFM on the 30FPI rad, compared with the F12's 40 CFM.

    If you are satisfied with the performance of the F12, stick with that. It is under warranty for another year, and should last longer than that. When it comes time to replace it, though, you might consider the 12x15 -- or they might have something better by then.
    Hello all. New to the forum.

    I have ben using a NF-f12 fan on the condenser of my 12v compressor refrigerator for close to 5 years.

    I replaced the original fan which was rated at around 72cfm and was sucking air through the condenser. The condenser is very similar in design to the finned heatsinks I see in the Noctua videos. the screwholes on the condenser line up with a 120MM fan.

    I installed the NF-f12 to push air through the condenser and the amount of time the compressor ran instantly was reduced by anywhere from 30 to 45 seconds. from over 5 minutes to under five minutes. That and the fan is quieter, and consumes 0.07 amps less, and I have been quite happy with my modification and the Noctua fan.

    This new Noctua Fan, one attached to a heatsink is claiming to outperform 2 NF-f12 in a push pull situation, yet the static pressure rating is but a fraction of the nf-f12. I get that cfm rating and SP ratings are not the end all be all of measuring performance, but what has gotten my attention, is the fan they are showing in the videos from the taipei show as Noctua newest 120 m offering in the A series, is showing a 9 blade impeller, yet the data sheets on the A12x15 shows 7 blades, unless I am missing something.

    If this new fan is as capable as two push pull nf-f12's at only 15 mm thick, well that extra 10MM is 10 more mm of open space behind my fan for it to scavenge air from, currently about 45mm clearance until the cabinet wall in which is resides.

    I could easily retask my current Nf-f12 and have been meaning to get another one to help exhaust a cabinet into which the heater condenser air blows and also houses Inverters and solar charge controllers. This New fan would seem to be a no brainer, but I cant get over the fan they are showing in the video having 9 wider blades. In fact I see no Noctua offering in the 120 or 140Mm size which has 9 blades.

    Is is possible this single fan outperforming the push pull dual nf-f12s is not the a12x15?

    The one fan shown in the beginning of " Over four years in the making, Notcua’s A Series fans are finally here" video on youtube, looks like no Noctua fan I can find in their lineup. The Impeller looks more like a gentile typhoon.

    What Am I missing?
    How did you mount this fan to radiators without the screw hanging out 5 mm? I can't seem to find what size screws I would need and it doesn't come with them :(

    Standard screw length for 25mm fans is 30mm. So 20mm screw for a 15mm fan sounds right.
    The NF-A4x15 costs $15. The San Ace non-PWM retails for $22 -- 50% more; another league. I got mine in a lot of eight when the reseller ordered too many for a customer. That is the same: "Silent" fan that Seasonic puts in the X-Series PSU's. It competes with the Gentle Typhoon. If you can get a PWM in the "Silent" series, get one. I believe the 9S1212P4M011 is the only PWM they make on a routine basis, but any of the manufacturers will make you anything if you pay enough.

    @bzh2 and @||Console|| - you generally buy a screw that is 5mm longer than your fan is thick. Most rads use 4mm scews, though I have seen a 3mm screw.

    it was just a rough guess
    thank you for all that info. it helps!

    so if i look at the 3rd chart (30fpi usage). its saying that the a12x15 is pushing 46cfm while at 27 dB? so in that case the san ace silent M pushes 55CFM at 26dB? that san ace seem to be really well balanced then, right?

    The NF-A4x15 costs $15. The San Ace non-PWM retails for $22 -- 50% more; another league. I got mine in a lot of eight when the reseller ordered too many for a customer. That is the same: "Silent" fan that Seasonic puts in the X-Series PSU's. It competes with the Gentle Typhoon. If you can get a PWM in the "Silent" series, get one. I believe the 9S1212P4M011 is the only PWM they make on a routine basis, but any of the manufacturers will make you anything if you pay enough.

    @bzh2 and @||Console|| - you generally buy a screw that is 5mm longer than your fan is thick. Most rads use 4mm scews, though I have seen a 3mm screw.

    use any 6/32 screw cut to length you want

    Thank you, yeah i understand that part, I was more hoping to find out what length screws these would be, 20mm I assume but I know I'm going to end up buying like 9 different sizes.
    How did you mount this fan to radiators without the screw hanging out 5 mm? I can't seem to find what size screws I would need and it doesn't come with them :(
    thank you for all that info. it helps!

    so if i look at the 3rd chart (30fpi usage). its saying that the a12x15 is pushing 46cfm while at 27 dB? so in that case the san ace silent M pushes 55CFM at 26dB? that san ace seem to be really well balanced then, right?
    . . . those graphs, . . . how to read them.

    Pick your condition -- case/heatsink/rad -- then pick a chart and look at the middle stripe.

    Indeed. They were picking a very good fan to compare it with. I believe the blade angle makes the difference. I can't prove it though. But this fan reminds me of GT's.

    3dB doubles the power, and it is the perceptual threshold, where the normal listener can tell that one item is louder than another. But at 10 dB something is perceived to be twice as loud as something else.

    You are correct, except that the only identical comparison is an unobstructed fan, so all companies use that as a spec, even Noctua. All airflow specs are impractical, which is why we test them. And the NF-A12x15 indeed shines.

    It differs from rad to rad. You have to know your own equipment.
    These were Real World Tests (tm).

    So go back and commune with the information. It will repay you to do that.

    thank you for the info. yeah, i agree there is a lot of info in those graphs, i jsut cant seem to understand how to read them. i may be a bit slow.... also, i dont tend to spend much time looking at fan graphs so im sure there might be a little learning curve.

    i was unsure if i could post links. thats why i said to go to you tube and search that exact phrase. the first video shows the heatstink and test they had. it was semi real world and it showed that 1 a12x15 matches 2 nf-f12's. i was hoping someone with the right gear could confirm that test. i know most fans seem to fall in a margin of error of each other. but i have seen other scatter plots that at least narrow down bad fans from good ones. with these 2 specific fans im sure the plots would be similar, but i would still find it very interesting to see where/how they do in that regards.

    it seems like the a12 is much better from what you are saying. isnt 3db a big difference as far as actual percepted noise? so its just as good as a f12, but half as loud? i thought i read somewhere that sound doubles every 3db?

    also, like you said how the the f12 performs better in open air. thats the point that noctua makes in the video, that many fan companies test in ways that are not practical. so on spec sheet, a certain fan might have a higher CFM (when tested with 100% obstruction). but in real world on a rad, it could be worse. thats where they say the a12 shines, in real world situations, in a case, on a heatsink or on a rad.

    if the a12 was 6cfm better i am curious what that means in reagards to temps? is it 1 degree better, 5 degrees or none?
    BTW -- in you 2d paragraph, you note that the NF-A12x15 beat an NF-S12A in a case (presumably through a dust filter). That is exactly what the first chart shows.
    These were Real World Tests (tm). I did cooling tests on a heatsink with fans back in 2009-2010. Those tests did not differentiate fans enough. Sometimes there was only a fraction of a degree between fans, and the SPL testing was open to many vagaries.

    Now that I have anemometers I can test airflow directly. These are not tests where you see fans matched by RPM. That always seemed artificial to me. These charts are set up so that the SPL, airflow under the test condition and airflow unobstructed (a non-realworld testing point, useful only in comparing to specification), are set up so you can compare various fans to each other under three realworld conditions: through a dust filter (for case fans), through a 16 FPI rad (a proxy for the average heatsink) and through a 30 FPI rad.

    You basically pick your fan usage, find your fan and compare it to others.

    The gravamen of the charts is the middle column, the one that changes color as you step through the charts. You just have to spend some time looking at them, letting the data speak to you. You cannot just look at the charts and pass on. There is too much information for that.

    In the second chart you can see the NF-A12x15 and the NF-F12 side by side. The two fans were dead even in airflow with the through the 16 FPI rad. The NF-A12x15 was 3 dB quieter than the NF-F12 (in unobstructed airflow the NF-F12 was better; shows how non-realworld that measurement is). When pushing through the 30 FPI rad, the third chart shows you that the NF-A12x15 was 6 CFM better than the NF-F12.

    In my reviews the test conditions are stable. I use the same measuring tools, the same filters and the same rads for the fans. You haven't said which heatsink Noctua was using to show off this excellent fan. I suspect that it was a tight heatsink, presenting more obstruction than a 16 FPI rad. They can do that, but I picked a rad that is a proxy for an average heatsink; many of them provide less obstruction than a 16 FPI rad. This rad was chosen because it presents an obstruction that is average for a large number of heatsinks.

    So go back and commune with the information. It will repay you to do that.