The Recommended Fans article is finally updated. It is a concise practical summary about the technologies, techniques and art of using quiet fans in computers, along with a list of the best candidates.
- Sept 26, 2012: Complete rewrite & update of contents and recommendations
- March 4, 2007: Updated and substantially rewritten to reflect
the results of our fan test project - August 26, 2004: Added info on comprehensive fan project
and added more fans to the list, including 92mm and 120mm models - January 5, 2003: Minor changes
- December 24, 2002: First publication by Mike Chin
Silent PC Review has been interested in fans since its inception, way back
in 2002. This is no surprise — fans are the primary noisemakers in most
systems, and SPCR is a site about computer noise. However, for the first four
years of its existence, the vast majority of SPCR’s fan knowledge was buried
in personal forum posts and the occasional mention of a particular "reference
fan". No formal fan reviews were done until November 2006.
The first baby steps towards reviewing fans occurred in early 2004, when we
announced a project called Calling
All Good Fans — intended to be a comprehensive examination of the
best fans available. A quick glance at the list of updates above shows how long
this project took to bear fruit; this recommended list languished for almost
three years as SPCR’s knowledge of fans stagnated. Things got going again in 2007 and 2008 after another series experiments with fan testing systems. Still unsatisfied with our fan testing methodology, we went back to the drawing board, and came up with the basics for a new system in Fan Test System, SPCR 2010. Finally, couple months ago, another fan roundup was posted: Fan Roundup #6. This was a substantial empirical improvement over the previous tests as it was the first conducted in our custom-built 11 dBA hemi-anechoic chamber with acoustic instrumentation capable of reading accurately down to 9 dBA.
WHAT MAKES A GOOD FAN?
While there are numerous dimensions to fan performance, SPCR’s recommendations
are based on two:
- Noise
- Effective cooling
NOISE
It’s well known that the amount of noise a fan
makes is based largely on rotation speed, so it might seem that we should just
recommend the slowest fans available and leave it at that. However, that doesn’t
quite cover what we mean when we say a fan has low noise. Thanks to the widespread
use of fan speed controllers, a fan’s rated speed is almost irrelevant when
it comes to choosing a fan — computer fans are very rarely used at their
stock speed, especially in custom-built silenced systems. Besides,
almost every fan on the market is too noisy at full speed.
Reducing the speed of the fans is a mandatory step in silencing a PC.
Our recommendations assume that a fan controller will most often be used to reduce the
fan speed. When we evaluate fan noise, we weigh our conclusions most on how a fan sounds
when it has been slowed down to an acceptable level. What is an acceptable level?
There are two rules of thumb here:
- A fan should be slowed down to the point where it provides enough
airflow to prevent overheating. - A fan should be slowed down to the point where there is no acoustic benefit
to reducing the speed further — i.e. the fan has become inaudible.
Both of these rules are system- and user-specific; it is impossible for us to know what
the ideal speed for your system will be.
There are other critical aspects of noise, beyond what we can easily measure. Anyone who has even scratched at the science of sound and noise knows about SPL or sound pressure level, which we routinely measure in decibels, weighted to the A scale, which most closely approximates the frequency and amplitude response of human hearing. This is a basic measure of "loudness" or amplitude. These SPL measurements are conducted with an extremely sensitive, low noise microphone capable of accurate readings down to 9 dBA in our own hemi-anechoic chamber, which has an ambient noise level of 10 dBA. But beyond SPL, there are other sonic factors:
Tonality: This is the subjective effect of a sharp audible peak in
amplitude. It sounds like a tone, hence the word tonality, and its opposite
is "broadband" or "random" noise. The latter is described
as white noise when the frequency balance is flat from low to high frequencies,
and called pink noise when the amplitude falls with increasing frequency.
Pink noise is more common in nature, and it’s the desired "character"
for any noise if you want it to be unobtrusive. In general, random noise is
far less objectionable than tonal noise.Regular or irregular variances: This term is a catch-all to cover a range of fan noises that are not constant, but varying. "Ticking" is a pretty common phenomenon. It can be regular and vary proportionately with RPM, or irregular and somewhat random. It can also vary depending on the angle and position in which the fan is used. Depending on its amplitude, and the ambient noise floor of the computer or its environment, this noise can become quite annoying. "Chuffing" is a variation of the above, but the sound is stretched over a longer frame of time. There are other terms describing other noises, but what they all have in common is that they are not desired, they can be annoying, and they are not constant. Absence of all such noises is the ideal; very few fan actually exhibit this.
EFFECTIVE COOLING
The second aspect of fan performance is what we describe as "effective cooling". This phrase is used in preference to "airflow", which does not have a linear or even linearly proportionate relationship to cooling. We tried for years to improve the accuracy of our airflow measurements, but in the end, we concluded that a $40,000 fan testing machine is beyond our reach, and that knowing the airflow really doesn’t matter anyway in the context of quiet PC cooling.
Cooling in a PC depends on several interrelated factors. The relationship between measured airflow, pressure and temperature change is non-linear even for a single combination of heatsink + CPU and fan. It never scales up and down in a linear way.
So our current fan testing setup measures noise at various speeds, and the cooling effectiveness of the fan with a particular heatsink and heat source at those various speeds. The heatsink used has what we’d consider "medium" airflow impedance — it is neither very difficult nor very easy for a fan to "push" air through it. The word push touches on another technical parameter we’re choosing to not measure: Static air pressure. This describes the ability of a fan to "push" air through varying impedance, which is important, for example, for good cooling performance with a heatsink that has big, tightly spaced fins.
While our recommendations are based mainly on how the fan sounds at low speeds,
this is not the only thing we examine.
A near-complete run-down of our test procedures and tools can be found in Fan Test System, SPCR 2010. Slight changes were noted in Fan Roundup #6.
QUALITY AND RELIABILITY
Aside from noise and effective cooling, reliability is another consideration. Unfortunately, build quality and reliability is impossible to test
without long term study with a large sample size. Such testing is well beyond
the resources any free hardware review site, so we are limited to making educated guesses about fan quality. There are a number of factors that affect our
judgment of quality, some of which are listed below.
- Bearing type — ball bearings appear to last longer than sleeve and other bearings, but this is not universally agreed.
- Rated MTBF — how long the manufacturer thinks the fan will last. Not
all manufacturers are trustworthy in this respect, and interpreting what MTBF
means exactly can be challenging at the best of times… - Manufacturer — some manufacturers are known to be generally better — or
worse — than others. - Sample Variance — high sample variance suggests poor quality control,
and thus a higher chance of some kind of failure. - General Build Quality — this covers everything from the type of plastic,
to the fit and precision of the molding, to the presence of "wobble"
while the fan is spinning. Basically, anything that appears to be out of the
ordinary is enough to raise our suspicions.
One thing to keep in mind that if you use fans the way we recommend — at reduced speed — they should last much longer than usual. With a decrease from rated RPM, there should be a proportionate increase in run time. Our 10+ years experience in the lab suggests longevity is much less of a concern for quiet PC enthusiasts because we run fans much slower than they are rated for. We’ve had very few fans over the last 10 years that become too worn out or too noisy to remain in service.
Notes on Sample Variance: Where possible, we try to examine more than
one sample of a given fan model, as sample variance is often quite high among
fans, especially for "minor" attributes such as noise. Not only
is good consistency between samples helpful for ensuring that you don’t get
a bad sample, it is also an indication of good quality control at the factory.
One uncontrollable variance is that rough handling (like dropping a box of
fans several feet) at any point during a fan’s journey to SPCR (or the cumulative
effects of many instances of rough handling) can cause subtle bearing damage
that affects its noise. We always ask for the fans to be packed like thin-shelled
eggs, but damage could have occurred before they’re shipped to us. This type
of damage may be subtle enough that very few users would actually notice and
return or report such samples, and yet we might mark those same samples down
for poor acoustics. Without huge sample sizes, we really have to shrug and say
we do the best we can.
CONTROLLING THE SPEED OF COMPUTER FANS
There are many ways of control fan speed.
• Modern motherboards all have some form of fan speed control
for at least one or two fan headers, particularly the 4-pin CPU header for
the PWM fans that are now standard in all stock Intel (and AMD) CPU coolers.
These can usually be controlled in the BIOS and/or via a desktop utility from
the motherboard manufacturer, and often with SpeedFan.
Most often, the fan speed is tethered to CPU temperature sensors, and varied
automatically in accordance to preset profiles, and sometimes with user-defined
profiles. The number of controllable fan headers (both 4 and 3 pin) and the
flexibility of the control system varies tremendously, with the best, most
flexible controls usually appearing on the most high end motherboards. To
date, the Fan Xpert 2
from ASUS featured on many of their Intel Z77 boards is about the best
we’ve seen. Often, in quiet PCs where relatively few fans are used, the motherboard
fan headers are all you need to speed-control the fans.• For those who want a simple control for a single 3-pin fan, a variable
voltage controller like the Zalman
Fanmate 2 is ideal. It is a small, inexpensive voltage controller with
a tiny knob that sits between the motherboard fan header and the fan, providing
a range of 5 to 11 volts. Cost is usually ~$5. These devices
can also be built for as little as a dollar or two if you are handy with
a soldering iron.• A rheostat is a simple high power variable resistor that allows
fan speed to be controlled much like with a voltage controller. It is often
more expensive and less energy (heat) efficient than most variable voltage controllers.• For more elaborate, multiple fan control, products with names like fan bay, bay bus, and so on, are available. These generally occupy a 5.25″ drive bay on the front panel of the PC case and allow control of 2 to a dozen fans, with a variety of features and options, including thermistor control. They range in price from US$10 to $100.
•
The 5V and 7V tricks: These date back to hardware hackers before SPCR, but are still used by those who prefer simplicity. Do-it-yourselfers often tap into the voltage lines
available from any PSU. Three conveniently available voltages can be obtained
from the standard 4-pin Molex connector: 12V (yellow), 5V (red), and 7V (the
difference voltage between 12V and 5V). The 7V line is not really
that, and it is not recommended for more than one or two fans, especially
if they draw much power. For technical reasons we won’t cover here, it can
potentially damage the PSU. For typical fans, however, it is usually
perfectly safe with a good quality PSU.• Switches can be configured for multiple voltage feed to fans
using the basic wiring information shown here. The DIY
12/5V switch is one example. There are many more variations that have
been described in the SPCR Forum and all over the web. Your imagination is
your main limitation.• A simple way to get 6V is to wire two identical fans in series to 12V.
• Resistors in series (at least 1W rating) with the fan can also be used. 50~60 ohms usually provides around 5V from a 12V source. Adding ~25 ohms to 5V will give you around 4 volts. The numbers are approximate because the inductance/capacitance of the fan will affect the voltage drop.
• Zener diodes can also be used to reduce voltage — but
still allowing the full 12V to pass on startup.
USEFUL LINKS
In SPCR
- Fan Test System, SPCR 2010
– Detailed information about fan acoustics & performance, and our testing evolution. - Anatomy of a Silent Fan
– A technical run-down of all the technology that goes into a fan. - Get 12V, 7V, or 5V from
your Fans – A quick outline on how to obtain a lower fan voltage from
your power supply without buying an external fan controller.
On the Web
- Comair
Rotron Engineering Tools – fan manufacturer. Great collection of articles
that address a wide variety of topics related to fans and cooling. - NMB
– Ball vs. Sleeve: A Comparison In Bearing Performance – The
case for ball bearing fans. Lots of other good info at NMB Fan Engineering and NMB White Papers - TelCom Semiconductor: Suppressing
Acoustic Noise in PWM Fan Speed Control Systems (pdf) - Fan Noise Solutions
– Enthusiast web site, by cpemma – R.I.P. Both site and cpemma have passed - JMC – Specifically,
news info on Panther Fans, PWM fans, and technical paper on Fan Noise. - EBM/Papst –
fan manufacturer. Some very good articles in their Tech
Articles section. - Fan Speed Control
Techniques in PCs by David Hanrahan (pdf) from Analog
Devices - Dorothy Bradbury:
Silent & Industrial Fans: The web’s resident expert on fan bearings
and reliability… appears to have retired.
THE QUIET FAN LIST
SPCR’s
recommended fan list is divided into four sections, one for each common
fan size: 80mm, 92mm, 120mm and 140mm or larger. Most fans in these tables have been tested by SPCR
and found to be of the highest standard. Some previously recommended fans, such as the Scythe Kama Flow, have been removed because they are discontinued.
The summary data here should be mostly self-evident. Under RPM is listed the lowest consistent start speed, and the maximum speed (at 12V). Under SPL is cited the measured noise in dBA@1m at those lowest and highest speeds. Finally, under Cooling is shown the actual measured temperature rise (in °C) at a measured SPL. This data is drawn from the new test system; at this point, there’s only one roundup (Fan Roundup #6) where the new test system was used. Where the data is accompanied by an asterisk (*), it is the manufacturer’s specification (for fans we haven’t officially tested).
With the Cooling data, the ideal is for both numbers to be low: Low temperature rise and low SPL. You will note that the SPL is not the same for all the fans, though it is mostly between 12 and 16 dBA. That is because the SPL is not the test reference — specific RPM points are the references. It would be more convenient here to have some preset reference SPL like 15 dBA@1m, but this is not easy to do because SPL is much harder to use as a reference, you cannot "dial it in" like you can voltage or RPM, it is a derivative of the fan speed. Then there is the further issue of which SPL point? With very slow, quiet fans, the SPL barely exceeds 12 dBA, and with some higher speed fans, the minimum SPL might be as high as 17 dBA. So accept the info as it is — a summary of cooling performance vs noise — and for full details, read the reviews!
| Recommended 14cm (& bigger) Fans | |||||
| Fan Model (linked to review) | Manufacturer | Bearing Type | RPM | SPL dBA@1m | Cooling |
| ?? | ?? | 370~1000 | 11~26 | +23°/15dBA | |
| An unusual large PWM fan from Therlmaright, Taiwan’s longest-lived performance heatsink maker. Meant for use on a heatsink with a big interface between fan and fin stack, the TY150 isn’t quiet at full speed but gets much better as speed is reduced. Starts consistently at 37% PWM power. Works beautifully on a big heatsink like Thermalright’s own Archon SB-E. Added Sept 2012 | |||||
| Phanteks PH-F140TS | ?? | UFB | 650~1350 | 14~32 | n/a |
| Not officially tested, except in the context of the Phanteks PH-TC14PE Dual Fan CPU Heatsink, for which it is the official stock fan. Hype-rich as usual, but this 14cm fan has merit, sounds smooth and offers decent cooling. Should work fine as a case fan as well. Added Sept 2012 | |||||
| Noctua NH-C14 | ?? | SSO | 610~1130 | 12~27 | n/a |
| Like the Phanteks, this Noctua has not been officially tested except with Noctua’s own coolers. It’s a decently quiet fan though not the last word in either acousitcs or cooling performance, and a bit pricey. Added Sept 2012 | |||||
| Antec TrueQuiet 140 | ?? | sleeve | 500/800* | 9.8~20* | n/a |
| Not officially tested, but similar in acoustics to TQ 120, very quiet though not the best CPU cooler, better for case cooling Soft corner insets (probably borrowed from the NB M series) keep vibration away, 2-speed switch is useful. Good availability & modest pricing put it on our list. Added Sept 2012 | |||||
| Recommended 12cm Fans | |||||
| Fan Model (linked to review) | Manufacturer | Bearing Type | RPM | SPL dBA@1m | Cooling |
| ?? | NB-NanoSLI | 300~870 | 10~12 | +25°/12dBA | |
| It has multiple unique features like soft rubber corner blocks for highly effective vibration damping, and it is just about the quietest fan we’ve tested at full speed. It also manages good cooling even at the slow <900 RPM speed. Very nice for silent computing. Added Sept 2012 | |||||
| ?? | NB-NanoSLI | 540~1265 | 11~23 | +25°/13dBA | |
| Higher speed version of the S1 with the same basic performance. Slows down nicely w/o spurious noises. More versatile due to higher maximum speed. Added Sept 2012. | |||||
| ?? | NB-NanoSLI | 600~1600* | 7~23* | n/a | |
| PWM version of M series. Higher speed M12-P was tested & found to be a bit too high speed to be useful in a silent PC. We’re sure the PS offers performance similar to the S2 but with the advantages of PWM control via the motherboard. Added Sept 2012 | |||||
| Nexus Real Silent Case Fan D12SL-12 | Yate Loon / Hong Sheng? | Sleeve | 650~1100 | 12~18 | +24°/14dBA |
| A longtime favorite, still recommended. SPCR’s de facto reference 120mm fan. Its noise character is smooth, generating a low hum when it is audible. It manages to provide consistently better cooling on most heatsinks than most 120mm fans. Sample variance is a bit of a question mark. Added Mar/07 | |||||
| Nidec | Double Ball | 340~880 | 11~12 | +24°/12dBA | |
| High quality build, heavy duty bearings and a smooth acoustic profile, excellent cooling to noise ratio. The 1450 RPM GT 120-14 was also tested, not quite as quiet and developed high pitch tonality when slowed down. 550 RPM #11 is probably too slow to be useful; the 1150 RPM #13 might be a great all-arounder. Officially discontinued but still in the market. Added Sept 2012 | |||||
| Scythe Slipstream 12L, 12M, PWM/VR | ?? | Sleeve | 300~800 400~1200 | 19 max 28 max | n/a |
| Slipstreams have been recommended in the SPCR forums for years, ideally as case fans. The SPL data is from pre-anechoic chamber days, but there’s no question these fans are smooth and quiet, slow down gracefully, and start at very low speed. They’ve been widly popular for good reason. A PWM/VR version is now available, with similarly good characteristics. Added Sept 2012 | |||||
| ?? | Sleeve | 310~1200* | 23 max | +24°/12dBA | |
| High quality 7-blade fan, tested pre-anechoic chamber. Smooth& quiet: We liked it then, we still like it now. Added Sept 2012 | |||||
| Antec TrueQuiet 120 | ?? | Sleeve | 550~1100 | 11~19 | +26°/15dBA |
| Soft corner mounting pads (probably borrowed from the NB M series), and good acoustics, but not great cooling, with a convenient 2-speed switch to slow the fan to ~650 RPM. Modest pricing and wide availability out it on our list. Added Sept 2012 | |||||
* * *
| Recommended 9cm Fans NOTE: It has been ages since we paid close attention to fans of this size, simply because the 12cm fans have so completely dominated both case and CPU cooling for many years now. We will try and assemble a new 92/80mm fan roundup in the near future. If you really need them, your best quiet bets are <1500 RPM fans from Scythe, Noise Blocker, Noctua, Enermax and NMB. | |||||
| Fan Model (linked to review) | Manufacturer | Bearing Type | Starting Voltage | Rated Speed | SPL @ Full Speed |
| Nexus Real Silent Case Fan DF1209SL-3 | Dynatron | Sleeve | 2.4V | 1,500 RPM | 21 dBA@1m |
| Like its larger 120mm cousin, the 92mm Nexus has served as our reference fan for years. It set the standard for what a quiet fan should sound like: A low, smooth hum that disappears quickly. There’s a slight touch of motor whine at full speed, but that drops away when speed is even slightly reduced. Its main weaknesses? Sleeve bearings that are unsuitable for high temperatures and a low MTBF that suggests long-term reliability may be poor. Added Mar/07 | |||||
| Unknown | Sleeve | 3.9V | 1,400 RPM | 21 dBA@1m | |
| A slick looking fan with a black frame and transparent blue fins (not to be confused with the Noiseblocker Silent Fan SE2, which has a clear frame and an ugly noise character). Sounds very similar to the Nexus, but a close side-by-side comparison showed the Noiseblocker to have a slightly more tonal (and thus more audible) noise character. Very smooth, and becomes inaudible below ~7V. Added Mar/07 | |||||
* * *
| Recommended 80mm Fans NOTE: It has been ages since we paid close attention to fans of this size, simply because the 12cm fans have so completely dominated both case and CPU cooling for many years now. We will try and assemble a new 92/80mm fan roundup in the near future. If you really need them, your best quiet bets are <1500 RPM fans from Scythe, Noise Blocker, Noctua, Enermax and NMB. | |||||
| Fan Model (linked to review) | Manufacturer | Bearing Type | Starting Voltage | Rated Speed | SPL @ Full Speed |
| Bisonic | Sleeve | 5.0V | 1,500 RPM | 20 dBA@1m | |
| As with its larger brothers, the 80mm Nexus sets the standard against which all other fans must measure up. It is shockingly quiet even at full speed. In many systems, 20 dBA@1m will already be inaudible without requiring any undervolting at all. Its noise character is smooth and low, just like the other Nexus models. Our only real complaint is that it may be too quiet — such a slow fan pushes very little air, and not everyone will be happy with a fan that pushes 22 CFM at full speed. Added Mar/07 | |||||
| Scythe Kama Flow SA8025FDB12SL | Adda? (Sony Bearing) | Sony-FDB | 4.6V | 1,500 RPM | 22~23 dBA@1m |
| This is basically the baby brother of the Scythe S-Flex, which, as noted above, gives the 120mm Nexus a run for its money. Likewise, this Kama Flow gives the 80mm Nexus a tough challenge, with the final result a tossup, as the two sound more or less identical. Our samples produced slightly more airflow than the Nexus at full speed, though both are rated at 1,500 RPM. The Kama Flow’s biggest advantage is the use of Sony’s FDB bearings, and its biggest disadvantage is the impossibility of acquiring one outside of Japan. Added Mar/07 | |||||
* * *
SPCR Articles of Related Interest:
Fan
Roundup #6
Fan Test System, SPCR 2010
Anatomy of the Silent Fan
Simple Fan Controllers from Zalman
Get 5V, 7V, or 12V for your Fans
* * *
Discuss this article in the SPCR Forums.
