When I built my current computer, I wanted it to be quiet. Following quite many reviews, I went with the SilenX Ixtrema 120 Quiet Fans and got two for my case.
Compared to other fans, they are quite pricy, at about 16 Euro a piece in Germany, ordered online. So, with raving reviews and for that price, my expectations where quite high. I put them in the most crucial places of my computer, right behind the CPU cooler at the upper far edge of my chasis.
I was impressed with the fans, I could hear them with no problems, two rooms away, or in other words, through a closed door... They are loud, compared to those that came with the Antec chasis, I have. Anyway, since I needed two more fans than came with the chasis, I let them in place. They actually do cool down the inner chasis quite well, and running the CPU and memory a bout 30% above specs, cooling is priority number one, no more extra heating for my office required in the winter.
Well, living with a quite noisy computer for about 150 hours of actual working time, I had a big *bang* inside and one of the Silenx fans shattered quite loudly. The blades came apart in three pieces and went through the whole inside of the computer. Replaced it with a spare fan I had, the computer was quieter and according to the inside thermometer, temparature was up by about 2.5°C.
Another 200 hours later, yesterday evening, the second fan broke into three pieces with a loud bang. Luckily though, this time it did not send those pieces through the whole chasis... I replaced it with another spare one (last I had *g*) and now the computer is really quiet. Temparature does not seem to go up any further, though I did not test it yet. Will do that soon. After 30 minutes at about 75% CPU work time converting 350 DNG (RAW images) to JPEG, the CPU was at under 45°C, which is great for an Intel Quad-Core, currently overclocked at 25%. Will test it at 30% and full load soon.
I will let you know what fans I am using now, when I have let them work a little longer. But they are really quiet compared to those SilenX Ixtrema 120 fans. Extreme they are ;-)