I bought some Arctic fans before and as the picture shows the last wire of the 4pin conector is not sleeved and has a seperate conector (yellow wire) which is ugly and I ended up cutting out =D But they do allow you to daisychain other fans so I had 3) 92mm fans powered from a motherboard with only one sistem fan header =)
well, they do that so you can connect it to a 3 pin header.... the yellow wire sends the rpm signal back to the mobo, otherwise, the computer will just tell the fan to run at full speed all the time.... i'm just wondering if the arctic is really just 20 dba....
I haven't had the pleasure of using either brand so I have to go by the specs. Get the Akasa Viper. You can always get a 7V or 5V adaptor for it if you find it to be to loud. and the CFM will still be the same (if not better) than the Arctic.