Six fans under test (rated RPM and dBA, measured grams, measured RPM at 4100ft after 15 min. warmup), price, U.S. source. The Scythe fans are the new S-Flex models.
Scythe SFF21D 800RPM "8.7dBA" 175g 900RPM $15 Heatsinkfactory
Scythe SFF21E 1200RPM "20.1dBA" 177g 1270RPM $15
Akasa AK183-L2B 1400RPM "18dBA" 101g 1450RPM (not recommended)
Global Win NCB CS 1300RPM "19dBA" 136g 1360RPM $8 Coolerguys
Cool-Master SUV 1220RPM "22dBA" 117g 1230RPM $4 Clubit
Sunbeamtech LED 1200RPM "21.75dBA" 106g 1335RPM $6 SVC
My personal criteria in evaluating fan noise is that I don't like mechanical noises at all
. I hate clangs, whines, scrapes, anything at all of that sort. Something continuous, such as air moving or even smooth sleeve bearing noise, doesn't bother me. I believe that, bearing noise aside, one fan will sound as loud as another at the same RPM as far as air-moving sound is concerned. YMMV.
In other words, I make a distinction between noise and sound. Now the comparisons.
Global Win Ceramic vs Sunbeamtech Silent LED: I had made this comparison before, but with a different Su and that time I couldn't tell the difference in sound/noise level, although the character of the sound was distinctly different. This time there was an obvious difference: The Su was louder, and the difference was more bearing sound/noise (although a non-objectionable sound/noise). I was using a different Su fan; the previous one had been mounted in a chassis. Same GW fan unit.
Global Win vs Scythe SFF21E: A repeat of the previous comparison. The 21E was louder, and the difference was the bearing sound/noise. Not as much difference as with the Su. Not an objectionable sound/noise.
C-M SUV vs SFF21E: 21E clearly louder, and again the difference was the bearing sound/noise. C-M bearing noise much less and lower in pitch. What little C-M sound/noise there is is pleasant.
Global Win vs C-M SUV: The two units' sound is very different in character. With that in mind, I couldn't detect a difference in sound/noise level. I could easily live with either fan.
Scythe SFF21D: Obviously nothing here to compare against. Very quiet indeed. Holding the fan 2 inches from my ear, the bearings made a very low, pleasant noise/sound.
Akasa: No point in comparing it. First, because of the higher RPM. Second, because of the annoying whine that's typical of ball-bearing fans. The spec sez the Akasa is 4dBA quieter than the C-M SUV. My ear sez the relationship is just the opposite. At least.
Finally, Su LED vs SFF21E: Too close to call. The character of the sound is even reasonably similar.
The Su runs 105RPM faster than the C-M; that's about a 2dBA difference. This may account for most if not all of the difference I was hearing this time as opposed to the last time. The GW ceramic bearing fan is running fast as well (it's supposed
to run fast) which makes its sound/noise vs. the other fans all the more surprising. It's a clear winner. I'm gonna buy a few more from CoolerGuys. If you like slow fans, you'll love the SFF21D; I have a spot for some of those. The Akasa is for ball-bearing lovers only (there are some of those!).
Remember we're only looking at a single unit of each fan here (2 of the Su counting my last comparison). How much variance is yet unknown and your reports can help in this regard.
I've made no effort to evaluate the various fans at lower voltages. I wanted to get this brief report to you this year.
Addendum next day:
I decided to see how the other fans would compare to the "800RPM" S-Flex fan. My sample turns exactly 900RPM here at 4100ft, so I set the C-M, Su, and GW fans one at a time to 900 with a Spire fan controller and compared them to the S-Flex 21D. In terms of increasing noise: GW, C-M, Su, 21D. But the 21D starts
at 900RPM, 12V so if you want to go down to 500Hz, the 21D is the unit to have. At a distance of 1 foot, I could barely hear any of them and at 1 meter closed up in a case, forget it!
I also compared the GW, C-M, Su and 21E at exactly 1028.57RPM. That's the order they finished in, quietest to noisiest. None of these fans had any objectionable noise/sounds, it's just that some had more, some had less.
The GW has one issue: it does not like to shove air toward the center of the earth. A Nexus Silent 92mm has the opposite problem, it doesn't like to shove air away from the center. Reviews of the XP-90 sometimes find suck mode works best (air going up on the test bed), sometimes push mode (air going down on the test bed). In a tower case, the XP-90 pushes air sideways no matter how you mount the fan, so this is not an issue.
The Su is different from the rest because of the shape of its blade - it curves more than the others. Looking at it from the back, there's more of a 'spoon' effect. This may be why the Su seems to push more air at a given RPM than other fans I've used. And we use fans not to get a particular RPM, but to push air. For this reason, I'm keeping the Su on my list. Right now I like the $8 GW, the $6 Su, and the $4 C-M. I like the rated 80,000 hour life expectancy of the GW.
I have no doubt that the future (perhaps the near
future) will bring us more quiet 120mm fans. There's a market for them. Competition will push prices down. SPCR seems to have a very conservative following, so I'm sure $18-$27 fans will continue to sell for awhile to SPCR folk.
Edit: added weight of C-M and Su; price and US source; and an addendum.