The Corsair SP (Static Pressure), AF (High Airflow) 120/140mm Fan Review
by E. Fylladitakis on November 25, 2015 8:00 AM ESTConclusion
The goal of our first fans review was to demonstrate the great performance difference that various fan designs can have and how these affect the selection of a fan for a specific application. It is also important to illustrate that merely the maximum static pressure and maximum airflow are not enough to represent the true performance of a fan, especially since both of these figures do not represent any real-world application scenario. Corsair's AF and SP series fans were ideal products for that purpose, as they are not "universal" models but each is designed for a specific application in mind.
Depending on the application, the selection of a fan can greatly affect performance. For example, if the fan is for a low impedance application (e.g. case fan without a filter), the AF140 would provide considerably more airflow than the SP140 and at a lower noise level. Similarly, the AF120 Performance Edition would provide about the same level of air volume flow at a much lower speed and noise level. On the other hand, if the fan is to be installed on a thick radiator, the AF120 would not manage to push half the air through it in comparison with a SP120.
As for the quality and performance of Corsair's fans, we first have to clarify once more that the LED and standard AF and SP fan versions are significantly different. This can also be noticed from the specifications of the fans, as the LED versions appear to have notably inferior performance than their non-LED counterparts. There is a reason why the LED versions are retailing for less. A twin pack of the AF120 LED fan currently retails for $18.40, while the AF120 Quiet Edition Twin Pack retails for $26 and a single fan for $18.20. The standard AF120, SP120 and AF140 fans are of both superior quality and design, plus they are using more expensive engines. By no means the AF140 LED and the SP140 LED are bad fans, but they do not really stand out like the immense static pressure of the SP120 Performance Edition does. If the lighting effect is not a necessity, we would definitely recommend the standard black version of the appropriate fan.
Corsair's advanced hydraulic bearing engine design is not ground-breaking, but it is clever. What Corsair did was to take the very widely used sleeve bearing design and improve it to match the reliability of a high end product. Sleeve bearings are known to generate comparatively low noise, especially when compared to ball bearings, but their lack of lubrication gives them relatively short lives. What Corsair did was to take a sleeve bearing and literally immersed it inside a tank of lubricant, alongside the axle of the engine itself. The lubricant ensures that the bearing will remain lubricated for life and also reduces friction and noise even further. That is where the name of this bearing design, "hydraulic", comes from. On paper, Corsair's hydraulic fan bearing can even outlast common ball bearing designs.
As for the engines of the LED fan versions, they might not have advanced hydraulic bearings as the rest of the series, but the rifle bearing that they are using is also considered a very good compromise between quiet operation, longevity and performance. They are not as premium as the hydraulic and FDB bearings that Corsair is using in their better fans, but they are definitely superior to a basic sleeve bearing fan.
To summarize, Corsair's fan products generally are of high quality and offer great application-specific performance, with the standard versions being even better than the LED versions of the seemingly same fan series. The SP series offer good performance for high impedance applications, such as coolers and radiators, while the AF series are designed to perform optimally as unobstructed case fans. Whether the LED version, the Performance Edition or the Quiet Edition is the right choice, that depends solely on the user's preferences, wants and needs.
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E.Fyll - Wednesday, November 25, 2015 - link
The word impedance is by no means limited to electrical resistance. Actually, electrical resistance and electrical impedance are different things to begin with.I can only assume that you are a new student if you have never heard of mechanical impedance. You definitely need to read more about it.
https://en.wikipedia.org/wiki/Mechanical_impedance
The resistance of a system to airflow is called impedance. Drag is the force that opposes airflow, generated by this impedance.
https://www.google.gr/url?sa=t&rct=j&q=&am...
Hulk - Wednesday, November 25, 2015 - link
Interesting. I have a BS in Mechanical Engineering from Rutgers and never heard the term impedance used to describe resistance to fluid flow. Not even in Fluid Mechanics where we spent about 5 weeks deriving the Navier-Stokes equations, which as you know completely describe all fluid behavior. Of course there isn't a closed form solution to these equations so complicated (real life) situations much be modeled via numerical computation.I have a feeling mechanical impedance is an older term that is rarely used anymore.
I think a much more descriptive term for this article would be to use the term "head" to quantify and describe the resistance to airflow through various computer systems as it relates to cooling. ie maintaining a certain rate of airflow though a case with a filter would have greater resistance (head) than one without a filter and thus require a different pump curve. Sizing pumps, which is what we are really talking about here is all about matching pump curves.
http://www.pricepump.com/pumpschool/psles2.html
But I think what most of us really want to know here is how much air a certain fan can move in a high head (resistance) situation and how much noise is makes, as well as in relatively low head situations. I think perhaps testing through a case with no filter would be a low head situation and though a filter would be a high head case. Perhaps testing though a relatively constrictive radiator would also be useful unless results were similar to the filter case. But once tested we'd know if both tests would be useful in the future.
Anyway, how much air flow (cooling)? How quiet? How long will it last? That's the bottom line.
Hulk - Wednesday, November 25, 2015 - link
Also I think most readers would better understand the term "head" for fluid resistance because it can be quantified as the height of a certain air column. ie pushing air case "x" with a filter is akin to pumping air an air column of "y" height, whereas removing the filter reduces the head (air column) height by z.E.Fyll - Wednesday, November 25, 2015 - link
Well, I can only assume that it depends on the school or the professor. Mechanical impedance is a very widely used term. You could run a Google Scholar search and you'd find thousands of papers published only this year.I think that I mentioned that already, but resistance and impedance are different figures. Resistance includes only Real parts. Impedance accounts for the Reactive parts as well.
Head is not resistance. Head is a measure of performance that is based on pressure. Practically, it can be converted from the left axis directly. Head = Pressure/404.3 for air, where head is in ft and pressure is in mmH20. It should generate a similar graph with a different Y axis.
Hulk - Wednesday, November 25, 2015 - link
Head is a measure of performance based on pressure and performance is exactly what you are trying to determine here. That's why I said head may be a better parameter rather than impedance. If you've worked in industry you've probably noticed no one (at least on the US East coast when it comes to pipelines or flow) talks about impedance but rather refer to "head loss." It's a working term, not a school/theory term.Oxford Guy - Thursday, November 26, 2015 - link
"It's a working term, not a school/theory term." That doesn't make it better. It just makes it common.Cold Fussion - Thursday, November 26, 2015 - link
I too have mechanical engineering degree and have never seen the term impedance used like how you use it in the fan curve graphs. Whenever I hear impedance used in a fluids context, it's normally electrical people trying to explain the resistance of a flow due to pressure. In the text books I've studied, what you describe as impedance in the curves is what would have normally described as the system curve or the system head or something along those lines.On a side note I find it pretty ridiculous that you guys have to actually do testing in order to get the fan curves instead of manufacturers providing a datasheet that has the fan curves on it (like they should be doing). I guess that shows the state of PC industry. I appreciate you guys doing real fan testing though and providing this data.
Erazor51 - Thursday, November 26, 2015 - link
E=mc2Freaky_Angelus - Friday, November 27, 2015 - link
LoL, let's throw titles as arguments...I've heard of impedance being used in fluid dynamics and, like the used mmH2O instead of Pascal, it's an older term used mainly by the 'old guard'. I would however recommend Anandtech to next time use Pa. as a term as you'll not find high tech fan-curve sheets using mmH2O (anymore).
On a side-note, if fan reviews are going to be used.. I would like to suggest a push-pull efficiency review on liquid coolers.
In the industry we almost always use pull configurations through heat exchangers as underpressure draws more evenly through an exchanger than otherwise possible with the momentum of the air. I don't have enough liquid coolers systems to be able to make a review, but my own pc is a degree lower. Considering some people might like to know these kind of things and I enjoyed to read something this close to my actual work, who knows.
Ohw, and just for bs argumentation and to be part of this thread: MSc.
mctylr - Wednesday, December 23, 2015 - link
I want to echo [Freaky Angelus]'s comments; mmH2O (millimeter of water) is a dated unit of measurement that isn't the preferred unit in any context as far as I know. It was essentially a metrication variation of inches of Mercury (inHg) that should be left to the history books. Pascals (Pa) would be the unit used for scientific literature in US and abroad. I'm not familiar with US engineering / commercial preferences for fluid dynamics and air flow/fan measurement to be sure, but I suspect they would prefer Pascals over mmH2O as well.