As I'm using several quiet computers for my work I've been comparing some 120mm fans lately :
Nexus D12SL-12 black & white (1000rpm), 8 samples (including some one-year old ones), â‚¬9.50 @ http://www.silentpcshop.nl
Scythe S-Flex SFF21E (1200rpm), 4 samples, â‚¬12.98 @ http://www.pcsilent.de
Noctua NF-S12-1200 (1200rpm), 2 samples, â‚¬19.00 @ http://www.alternate.de
SilenX iXtrema Pro 120/25 (1100rpm), IXP-74-11, 2 samples, â‚¬18.50 @ http://www.pcsilent.de
SilenX iXtrema Pro 120/38 (1200rpm), IXP-76-14, 2 samples, â‚¬19.50 @ http://www.pcsilent.de
Noiseblocker UltraSilentFan SX2pro (1550rpm), 1 sample, â‚¬19.50 @ http://www.pcsilent.de
[I'm living in Belgium; prices may vary a lot.]
Testing each of them at Â±800rpm gave me the feeling the cooling efficiencies were roughly equal, however noise signatures were not.
First let's say my sample of the Noiseblocker has a very disturbing 'turbine' noise somewhere in the 2600-2800Hz range; also I'm confident it would measure at least 6 dB/A @1m higher at Â±800rpm compared to all others.
One of my Noctua samples was dead on arrival. The other one was a nightmare noise-wise, the motor sounded like it was fighting against a knife. Packaging and shipping didn't seem to be in cause. The shop is sending me two new fans without asking me to send anything back.
Both SilenX 25mm samples were unexceptional in noise signature, somewhat more intrusive than the Scythe fans and probably 1~2 dB/A higher, too.
Both SilenX 38mm samples gave a very smooth, nice noise signature and seemed about as quiet as the Scythe fans; also they don't vibrate easily when hard-mounted inside a case. Currently using one on a daily basis inside my second quietest PC and I'm happy with it; now I'll have to see if it succeeds in the long-term.
The Nexus good samples provide a really pleasant noise signature that you easily forget; but 3 out of 8 samples were behaving badly. Such a high sample variance may not be to the taste of someone buying only 1 or 2 fans. I'm using the 5 good ones on a daily basis; 3 of them are one-year old and after having used them almost 24/7 I can't detect any deterioration noise-wise, compared to the fresh new ones.
The Scythe gives about the same noise signature as the best Nexus samples but all four Scythe samples behave the same, so it's my current choice for any further buy.
Obviously I'm looking forward for any future SPCR proper reviews too