SPCR

Getting ready for some fan measurements using my propellor-comparison method of achieving equal (but unknown) airflows on two fans, and then measuring the noise level up close (*real* close) on both fans. This should provide noise/airflow figures of merit for each fan.

I have a sample or samples of five of the 120mm fans SPCR has reviewed, four from roundup 4 and one from roundup 2.

120mm fans that I own sample(s) of: their RPMs at 25CFM as measured by SPCR , my dBA measurement at that RPM and 0.25" from the center of the fan's hub, SPCR's dBA measurement at 1 meter, from SPCR Fan Roundup 2 or 4 (*n), and the fan identification:

590RPM 35.8dBA (<19, *2) Scythe SFlexE
820RPM 44.2dBA (20, *4) SilenX
880RPM 40.2dBA (20, *4) YL D12SM-12
950RPM 44.2dBA (28, *4) Enermax UC12EB
970RPM 46.4dBA (20, *4) GW NCB
(my ambient noise level <30dBA, SPCR's ~18dBA)

SPCR measured a high 28dBA noise level on the UC12EB, noting a single tone noise. My UC12EBs (two of them) were purchased when the fan was first introduced and don't have that single tone noise. SPCR got 25CFM from the SFlexE at *what* RPM

To these 5 fans, I'll add the Scythe SlipStream 800 and do some one-on-one airflow comparisons, noting the noise level at 0.25" from the hub on each. This should be interesting!
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As I proofed the above words, the parts arrived. The $17 tachometer works, but in the interests of haste, I didn't use it for these first measurements. I'm gonna have to move the sensor propellor back - it tried to sync on the GW NCB RPM (but not other fans).

These measurements were made quickly but not carelessly. I've taken pics of the fixture, and will add them later as an edit. Here's the results I got for 4 fans:

As my standard fan I selected the GW NCB fan, at 970RPM. SPCR sez that's what it takes to get 25CFM. I measured 971RPM on the propellor - as I said, it was trying hard to sync (probably same pitch).

GW NCB 970RPM 971prop 46.4dBA (from above)
UC12EB 880RPM 971prop 41.8dBA (a sweet-sounding fan)
SFlexE 852RPM 971prop 42.3dBA (quieter than NCB!)
9blade 686RPM 971prop 40.5dBA Scythe SlipStream

My comments: aside from the 9-blade, the other 3 fan blades (by visual inspection) seemed to have very similar pitches. The SFlexE pitch was higher *near the hub*, but not at the edges of the fan, which is probably why its RPM is lower than the other two 7-blade fans.

How in the world SPCR got 25CFM out of the SFlexE at 590RPM I dunno. Either SPCR or I made a huge mistake. As I understand it, the only way for a 120mm fan to have that RPM advantage over another 120 is by having a drastically higher pitch... which the 9-blade fan does have and the SFlexE does not. Even the 9-blade needed almost another 100RPM beyond "590" to get the same sensor prop rotation rate.

Based on the highest RPM, the GW NCB fan has the highest measured noise and, presumably, the lowest pitch of these fans. I've always believed (and in one case, measured) that lower-pitch fans have an advantage in a typical PC case. My high regard for the NCB has always been for its performance in my cases.

Thus the caution: these are open-air measurements!

SPCR's fan noise measurements are very close to their room ambient noise, and perhaps below that for a fan or two. So differences of a couple-dBA get masked by the high ambient. I "close-miked" to avoid the room ambient problem. I had to block the sensor prop when making noise measurements; it was slightly unbalanced.

edit: added the following:

This fixture is made of white styrene .06" sheet. Note the small angle-brackets that locate all 25mm fans in the same spot, also styrene:





The $17 tachometer was not in use for these tests; I used my Extech stroboscope in the interests of getting done quickly. The fan is mounted on a 3/16" rubber strip and the entire fixture is supported by 9ea 3/8" square by 1/4" high "feet" made of very soft polyeurethane foam weatherstripping.

I didn't see a verdict section, so what's the bottomline?

Way too many technical terms for me ..from the info I gather, the Scythe SS blows the same amount of air at a lower RPM and lower sound. That must mean it's good.

Are the new Scythe SS fans worth it?

mtx wrote:I didn't see a verdict section, so what's the bottomline?

I've provided some noise measurements, all made under constant airflow (CFM) conditions in free air. [Fan measurements made in expensive acoustic testing facilities are also all made in free air.]

The simplest bottom line is, at constant airflow the fan with the lowest noise level wins. Alas, things aren't simple. For example, I did not report on the noise level of all SFlexE's, just on the one sample I have in hand. [Just as SPCR reported the noise level of the Enermax UC12EB fan(s) it had on hand.] But it's impossible for anyone to predict what the noise level will be of a specific fan you will buy tomorrow.

Also, most computer users do not actually use fans in free air. They mount them in computer cases most of the time. If the airflow in the computer case is restricted, this can impinge on the ability of the fan to perform its task. It's impossible for anyone to predict what fan A will do in case B using heatsink C on CPU D, which you may be overclocking...

I've provided some basic CFM/noise fan data. It requires some knowledge and experience to interpret. You can't download knowledge and experience off the internet. Alas, I can't provide it for you in a paragraph or two.

Felger Carbon wrote:

mtx wrote:I didn't see a verdict section, so what's the bottomline?

I've provided some noise measurements, all made under constant airflow (CFM) conditions in free air. [Fan measurements made in expensive acoustic testing facilities are also all made in free air.]

The simplest bottom line is, at constant airflow the fan with the lowest noise level wins. Alas, things aren't simple. For example, I did not report on the noise level of all SFlexE's, just on the one sample I have in hand. [Just as SPCR reported the noise level of the Enermax UC12EB fan(s) it had on hand.] But it's impossible for anyone to predict what the noise level will be of a specific fan you will buy tomorrow.

Also, most computer users do not actually use fans in free air. They mount them in computer cases most of the time. If the airflow in the computer case is restricted, this can impinge on the ability of the fan to perform its task. It's impossible for anyone to predict what fan A will do in case B using heatsink C on CPU D, which you may be overclocking...

Understandable and fair enough.

I've provided some basic CFM/noise fan data. It requires some knowledge and experience to interpret. You can't download knowledge and experience off the internet. Alas, I can't provide it for you in a paragraph or two.

I disagree.

Your job as a reviewer is to review and evaluate the fans in the most simplest terms. Think of it as a story or a lesson - you're the teacher, we (the audience) are the kids. You have to assume that we know absolutely nothing about fans (or very little) so your main job is to educate us more about the fans to aid us in our purchasing decisions.

To merely throw all the data on the table and leave it open for interpretation is not the best idea. Anyone can come in here, pick up any of the four fans you tested, and leave thinking they made a good decision, when in reality it wasn't the best decision. I'm not knocking on you and I appreciate the work and effort you've put into this project. I guess what I'm really trying to say is that you wrote the review - does it really hurt to add a paragraph or two, perhaps a summary or conclusion on which fan is the best?

mtx wrote:Your job as a reviewer is to review and evaluate the fans in the most simplest terms......

Im pretty sure Felger isnt a reviewer on SPCR. "Just" a silence enthusiast.

AuraAllan wrote:

mtx wrote:Your job as a reviewer is to review and evaluate the fans in the most simplest terms......

Im pretty sure Felger isnt a reviewer on SPCR. "Just" a silence enthusiast.

Sure, but he's been here awhile, he certainly knows what he's talking about, and he posted this under User Reviews . Am I really being that demanding and unreasonable ?

from the info I gather, the Scythe SS blows the same amount of air at a lower RPM and lower sound. That must mean it's good.

yes, I would say that is a fair conclusion from the above data. however, there is a caveat in that these experiments are conducted in free air and I suspect the Scythe Slipstream may have poor static pressure ability (for example on a restrictive heatsink or case) due to the rotor design; if you look at the Ultra Kaze or the new Noctua designed for high static pressure, they look very different from the Slipstreams.

jaganath wrote:[I suspect the Scythe Slipstream may have poor static pressure ability (for example on a restrictive heatsink or case).

I share your concern, and have from the start. That's why I put together a system using two of the SS fans for cooling (as exhaust and PSU fan, with the PSU fan not controlled by the PSU). I could find no problem with that system either noisewise or coolingwise. In particular, there were none of the problems that have been widely reported with the Noctua fans.

I cannot say that the SS is a worldbeater in such duty; I don't have enough data. I'm just saying I tried it; it worked; and I could detect no problems.

Another SPCR user has posted that he's going to try an SS fan on his TR 120SE shelf HSF. We need more such experiments to be performed, and the results reported here. Lots of people seem to be waiting for someone else to take the leap over an $8 - $10 item! Where is the spirit of adventure?

Am I really being that demanding and unreasonable ?

A little. What you provided would be good feedback for someone writing reviews for a living, but he is merely sharing data that he has gathered and making it available for us to use as we please. Maybe the title led you to expect more, but "Your job as a reviewer" seems you are expecting a little much or a little harsh on a knowledgable hobbiest sharing information.

Lots of people seem to be waiting for someone else to take the leap over an $8 - $10 item! Where is the spirit of adventure?

unfortunately the SS fans are not yet available in the UK, otherwise I'd be doing my best Errol Flynn impression.

Unfortunately I cannot just walk to my local store to pick up these fans.

I gotta order it from a city all the other way from the other side of Canada.

Shipping kills!

I revised the sensor propellor arrangement, and made provision not to measure double the true sensor RPM. These measurements of 120mm fans use the revised sensor and are arranged from lowest pitch to highest pitch.

YL SM 1041RPM 560prop 48.2dBA
GW NCB 970RPM 560prop 44.9dBA (NCB sample #2)
SC PWM 910RPM 560prop 48.6dBA Kama PWM 100%
AC PWM 902RPM 560prop 46.1dBA Arctic Cooling PWM 100%
UC12EB 880RPM 560prop 41.2dBA (a sweet-sounding fan)
SilenX 866RPM 560prop 45.4dBA "11dBA" version
SFlexE 852RPM 560prop 42.3dBA (quieter than NCB!)
9blade 686RPM 560prop 39.6dBA Scythe SlipStream

My conclusions: the new Scythe SlipStream fans are the quietest in open air, and also the highest pitch (lowest RPM). The Enermax Enlobal fan (my sample) is second, and (to my surprise!) the SFlexE is third. My YL SM sample and the two PWM fans are the loudest (highly undesirable). In the past, I compared fans at the same RPM, which I now know is a mistake.

My long-time favorite fan, the GW NCB, is the quietest low-pitch (high RPM) of this bunch. A low-pitch fan should do well in a PC-case environment.

Now, on to controlled-impedance tests...

I have some of the 800RPM and 1200 RPM models here, and I will run some tests shortly. I did the old "put hand behind fan" test, and I am shocked at how much air these really move at such quiet noise levels. Can't wait to see performance on a Infinity or TR Ultra120Xtreme.

FC, a question if i may.

you say, quote: UC12EB "..." (a sweet-sounding fan)

what do you mean by "sweet", exactly?

and a follow-up - GW NCB and UC12EB, from your subjective perspective, which sounds more pleasant?

mcoleg wrote:what do you mean by "sweet", exactly?
GW NCB and UC12EB, from your subjective perspective, which sounds more pleasant?

On just about all fans, the bearing noise has a degree of "gritty" noise. Some more, some less. On the UC12EB, this is completely, or almost completely, absent. I have no idea if this has anything to do with the advertised "magnetic suspension" (or something like that).

The UC12EB is more pleasant-sounding than the GW NCB.

Warning: SPCR's UC12EB samples exhibit a single-tone noise that my two samples don't have. Not all of these fans are the same, it seems.

ah, thank you sir, that makes sense.

looks like one will need to take a chance then. magnetic suspension has been done before, btw; one of the thermaltake's 70mm fans i think. dang, that thing was loud! high-pitched noise, as i remember.

i think i'll give UC12EB a try though, hopefully i'll get a good sample.

Just a thought...

Airflow doesn't always tell the whole story. There's a dead spot in the middle where the hub is, most of the airflow comes from the fan's edges. The Scythe SlipStream has a small hub. If mounted on the Ninja, it delivers more air to the core of the heatsink where it is most effective. Thus more suitable for some applications regardless of total aitflow.

Has anybody tested Arctic Fan AF12025 4-pin PWM?

Rebellious wrote:Has anybody tested Arctic Fan AF12025 4-pin PWM?

edit: Yes. I have and I did. It's the fan labelled "AC PWM" in the final test listing in this thread. As I've said before, too many fans, too few brain cells.

Felger Carbon wrote:

Rebellious wrote:Has anybody tested Arctic Fan AF12025 4-pin PWM?

I've used the AF PWM and the Scythe equivalent. I even took one of each apart. The IC motor controller is identical, the fans sound identical, and their noise levels measure the same with an SLM. For this reason, I chose not to include the AF and Scythe PWM fans in the above test.

Another SPCR member has posted that both PWM fans are made in the same factory, which would help explain the similarity of the two fans, noisewise.

I have one, it looks similar to the Scythe S-Flex except it's 1,500 RPM, but it has connectors for daisy-chaining 3-pin or 4-pin PWM fans and the wires are sleeved, kind of neat. I haven't used it yet. Do you think it's the same fan as S-Flex except for the sticker?


...

Rebellious wrote:Do you think it's the same fan as S-Flex except for the sticker?

Definitely not. It is highly similar to the Scythe PWM fan, however. Note that both the Sflex and Scythe PWM fans were included in the tests, with very different results.

Can you make a system that has a heatsink, let's say ninja or ultra 120 extreme, a power resistor attached to it's bottom and you control the voltage you send though, and then a temperature sensor also attached to the bottom.

Then you would decide the heating power and desired temperature, and try to achieve that with different fans, and see how loud they go?

That would give each fans true utility as a cpu fan. Maybe not as a case fan.

lm wrote:Can you make a system...

I probably could but I won't. I am not a public servant to spend hours toiling to perform your experiment. I don't know anybody else who will, either. The only person who is going to expend effort on your idea for an experiment is you.

I realize this is an impolite answer, but it is 100% truthful.

Sorry, I kind of didn't mean I'm asking you to make one, I'm just suggesting it as a way of measuring fans. I've always thought the you-passive could be used like this.

lm wrote:Sorry, I kind of didn't mean I'm asking you to make one, I'm just suggesting it as a way of measuring fans. I've always thought the you-passive could be used like this.

a better way of saying it would be could 'one' make a system...

sorry to resurrect this thread from the dead for a grammar nazi post.

Fayd wrote:could 'one' make a system...

Stormtrooper Carbon suggests "could a system be built...", which allows for two or more people to cooperate in building the system!

Ditto here~ï¼

I am very sorry to report to Felger Carbon's friends in this forum that I just learned today of his death last Wednesday.

Having known him for the past 25 years, I am very sad that we'll not be reading more of his SPCR (and other) exploits.

I will miss Felger Carbon. This is sad news.

Terrible News

TPeterson wrote:I am very sorry to report to Felger Carbon's friends in this forum that I just learned today of his death last Wednesday.

Having known him for the past 25 years, I am very sad that we'll not be reading more of his SPCR (and other) exploits.

Good God. I am deeply shocked and saddened to hear of Felger's passing. He would often send me friendly PM's with details of his latest fan test results and other matters of mutual interest. I only wish there was a way I could pay my respects in person, but sadly an ocean and several thousand miles prevent me. Hard to think of anything to say that isn't trite or cliché, but I'm sure he will be sorely missed by those who knew him best.