I have 3 of the SP120 quiet edition. They all come with little diodes (or whatever those things are) that can be placed between the 3-pin on the fan and the 3-pin plug you're connecting it to. That little thing will slow them down, but I don't know by how much. I'm sure all versions of their fans come with those.
I haven't actually been able to turn them on yet. I'm still waiting for a fan controller and I don't want to use them before I get a controller. I'm going to keep 2 of my case fans with blue LEDs.
The difference between the fan blades is that the large number of small blades will move air faster, but that can't create all that much pressure. The bigger blades will create better pressure, but they'd have to spin a lot faster to move the same amount of air.
They have been tested by the experts at Corsair and by multiple people who've bought both types.
The SP fans are for radiators only. AF fans are for everything else. Somehow you shouldn't even use an AF fan as a radiator pull fan. I don't know how that is, but it has been tested.
I'm pretty sure that the only reason they didn't give those fans 4 pins is to make people buy more fan controllers. Extremely few people would ever buy one if these fans had 4 pins.
quote harbin91
How loud roughly, is 24dB and 31 dB? What are they equivalent to? I can hear the fans in my current PC (not too loud), but if I have sound coming out of my TV, then I cannot notice any noise from them.
My previous CPU cooler DBX-B is rated to be at 20 dB and it was as loud as a microwave oven. I mean like pretty loud.
dB is not what humans define as loudness.