Silent Fans

Bian

Bian

Bian

Associate
Joined
12 Jan 2007
Posts
8
Hi Guys,

Does anyone know how silent PC fans work, what constitutes to them being silent, and is there a limit to the speed which they can opperate before making a noise??

Cheers
 
No fan is silent per se but some are very quiet.

Contributing to this are the design and quality of the bearings, the motor and the fan blades.

The speed at which the fan operates is proportional to the amount of noise it makes given the other factors so depending on how much air you need to move, larger fans tend to be quieter as they can run slower.

The quietest case fans I am aware of are 120mm and run at 800rpm with a noise level of 8dB which is to all intents and purposes silent.

Beware manufacturers claims of low noise & silence, many products are not.
 
Indeed its best to ask here for suggestions to get answers from people who have tried and tested the fans themselves, rather than rely on manufacturers claims of silence :)

For example, Akasa Amber fans, Vantec stealths and YS-Tech fans are all very quiet (in that order).
 
Helium_Junkie said:
Indeed its best to ask here for suggestions to get answers from people who have tried and tested the fans themselves, rather than rely on manufacturers claims of silence :)

For example, Akasa Amber fans, Vantec stealths and YS-Tech fans are all very quiet (in that order).
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Which order?AKASA quietest down to ys tech (louder?)
 
Using Yate Loons, much better than my Akasa Ambers I had, Noise blockers push a lot of air but are slighltly louder than the Akasa Ambers.
 
DRLIAMSKI said:
Which order?AKASA quietest down to ys tech (louder?)
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After testing (a lot) of silent fans I decided the best 80mm ones were the SilenX ones @ 11db and moving 18CFM. Although if you have an overclocked/hot PC you'll want something that moves more air.

:)

HTH
 
I've been impressed with the Noctua (1200) as a silent fan, side by side to an Amber it's quieter and pushes more air.
 
And, a bit more specifically, http://www.silentpcreview.com/article695-page1.html for 120mm fans compared:
There appears to be quite a bit of competition for the title of quietest 120mm fan. Of the six fan series that we tested, three are good enough for an SPCR recommendation, and the only real stinkers were the ARX fans.

In fact, there was enough competition that our longstanding favorite — the Nexus — was only the third best fan that we encountered, although the three top fans were so close that a 1-2-3 ranking isn't really fair.

The best fan of the bunch was the Noctua, which overcame our skepticism and lived up to its hype by producing more airflow at lower speeds. Its airflow-to-noise ratio is its best feature, which gives it enough of an edge to make up for its slightly rougher noise character. The Noctua has seen recommendations around the web, and we have no qualms about adding our own to the list.

Ranked in terms of noise, the Nexus and the Kama Flow / S-Flex should probably tie for second, but the better quality S-FDB bearings in Scythe's fans and the specter of sample variance for the Nexus are enough to secure second place for Scythe fans. We'll call the Nexus a close third.

Although the ebmPapst and Antec fans are not of the same noise caliber as the top three picks, they are close enough that some users will probably find other reasons to buy them. The Antec TriCool is a very good choice for casual users, as it is very widely distributed and its "Low" setting is good enough for systems that don't need to be inaudible. EbmPapst's 4412 series sounds good enough to redeem the company after the noisy 80mm fans that we looked at, and their reputation for quality and reliability is unparalleled. If security and reliability are requirements on par with noise and cost is of no object, the 4412 is your fan. Don't bother shelling out for the low speed 4412 F/2GLL though... the faster FGL model is just as quiet when undervolted, and sounds smoother to boot.
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and http://www.silentpcreview.com/article689-page1.html for 80mm fans:
It should be no surprise to regular readers that the Nexus is still the quietest fan that we know of. We've referred to it so often in our regular articles that most readers know by now that we think highly of it. What is surprising is how slim the Nexus' advantage is, especially when noise-for-airflow is taken into account. In fact, Scythe's obscure "Flow"-series fan is the equal of the Nexus in terms of noise and airflow, and may even be superior for reliability if its FDB bearings live up to their reputation. However, its extremely limited distribution outside of Japan will mean that most users will simply have no option but to continue using Nexus fans. Scythe, are you listening? There's an opportunity here...

There are a number of other fans that come very close to standard set by the Nexus: The unusual fans from Mechatronics and Arctic Cooling and, of course, the familiar Panaflo fans. In fact, both the Mechatronics and the Arctic Cooling may be quieter than the Nexus for a given rotation speed; it's only once airflow is considered that they drop behind a bit.

All of the fans mentioned above have smooth noise signatures, and they are completely inaudible from one meter when undervolted to produce 10 CFM. Any one of them would be quite at home in a quiet system so long as high airflow is not needed. The advantage of the Nexus and Scythe fans is that they are both reasonably quiet at 12V while producing a little more than 20 CFM each. This makes them very flexible: They can be used at a constant speed (~7V is a good bet) without being heard, or they can safely be used with a fan controller without worrying that the noise level will ever get too high.

Panaflo, the old standby, also lived up to its reputation so long as sample variance could be avoided. These fans are not so quiet at 12V, so they are a bit more difficult to work with, but they are well suited to situations where the Nexus or Scythe fans don't provide adequate cooling or a little more headroom is desired. They can always be turned down if the airflow isn't needed.

The rest of the fans in the test are less interesting, mostly because they don't sound good enough. Let's face it; most of the fans measured fairly close to each other, and most could be made quiet simply be turning them down far enough. Where they differed was noise character, and it was the fans that sounded bad no matter what speed they were at that fared poorly in this roundup
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jpmonkey69 said:
They didn't even try out SilenX fans, which IMO are the best CFM/Db.

120mm is 60CFM @ 14db, and 80mm is 18CFM @ 11db.
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Unfortunately it's rather well known that SilenX's airflow/noise ratings bear no resemblance to fact.
 
jpmonkey69 said:
source?
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A great many user reports on the SPCR forums, who take this kind of thing quite seriously. Would suggest a search there for more details.

SPCR themselves have also reviewed the odd SilenX fan, including this 11.8dB ( :rolleyes: ) model.

Googling "SilenX lies" or "Silenx male-cow-solid-waste ;)" should provide further opinion.
 
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You didn't read the 80mm roundup link then??

SilenX has a reputation for selling fans with absurdly low noise ratings, and the 11.8 dBA rating for this one is no exception — it's too low to be plausible. Fortunately, SilenX also has a reputation for being fairly quiet.

Evaluating this fan is somewhat difficult because it's thermally controlled, meaning it rarely, if ever runs at full speed, but it expects full voltage nonetheless. For the purposes of this test, we short-circuited the thermistor temporarily, causing the fan to run without the thermistor slowing things down. Assuming we can take SilenX' RPM specifications at face value, the fan's actual operational range should be the equivalent of what we heard between 5~9V. Knowing the way most thermally controlled fans work, there's a good chance that the fan will spend most of its time at minimum speed, which bodes well for noise.

SilenX sells to the retail market, and this fan looks the part. It comes in a color cardboard package that includes screws, rubber grommets for soft-mounting, and a Molex to 3-pin adapter for flexibility. All in all, not a bad package.

A tiny globe logo on the hub marks the fan as being sourced from Globe Fan, most likely. However, the mention of hypro bearings — supposedly unique to Adda — makes us wonder. Have we mis-identified the logo (unlikely, as we've encountered the logo on Globe's own fans), do Adda and Globe fan have a business relationship, or is SilenX playing fast and loose with the terms in their marketing material?

The fan spins quickly and noisily at full speed. No fan we've encountered is quiet at 3,000 RPM, and the Ixtrema held true to this rule. That said, it was quiet enough at 5V, and it still pushed a decent amount of air. We had to drop the input voltage down to 3.6V (just 0.1V above the starting voltage) to achieve 10 CFM for our constant airflow test.

Noise quality was nothing too impressive. It didn't disappear into the background like the Nexus, but the papery throbbing at 10 CFM was easy to ignore as background hiss. Above 5V, motor whine quickly became a problem, but it was still acceptable at its default speed around 5V.
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http://www.silentpcreview.com/article689-page4.html

Complete with graph and tables showing that their 11.8dBA rated fan produces 33dBA. They only produced less than 18dBA (still higher than their claimed figure) when dropped to below 3.6v, and at 18dBA they produced 10cfm. A far cry from their rated "32CFM @ 18db"
 
Marci said:
You didn't read the 80mm roundup link then??

Complete with graph and tables showing that their 11.8dBA rated fan produces 33dBA. They only produced less than 18dBA (still higher than their claimed figure) when dropped to below 3.6v, and at 18dBA they produced 10cfm. A far cry from their rated "32CFM @ 18db"
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Ahh Thanks. Some links don't open properly from work. Stupid proxy server.

I've tried a few types of fan, and tbh & imo always thought the SX was quieter. Maybe I'm wrong.
 
Noise is amazingly subjective, and it will vary wildly with what you are doing, what other noise sources are around, as well as case build, mounting type, where in the case the fan is mounted, ect ect. Even over that, some people will be more sensitive to different frequencies of sound, or find them more "annoying", so diff fans may be better for diff people.

For example, for me, i can barely hear my 120mm Ambers over my rather annoyingly loud PSU, and the read/write sound of my Raptor..... however once i get a damening caddie for the Raptor, and maybe fanswap the 80mm in the PSU, ill be able to better analyse what else to change.
 
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