Brighttail :
Are those DB with the stock fans on, cause if so, yes they are loud as they can go up to 2200 RPMS. I have lower speed SP fans on that go up to 1500 RPMS but usually ramp up no higher than 1000RPMs so it is QUITE quiet and keeps everything at 25C idle and 50C full load with a 4.6 OC on a 4670k.
The H100i spins at about 2700 rpm .... two problems with switching fans....
1. Add two $29 Noctua 1500 rpm fans and you cost is now $190 ....
- $50 more than the Swiftech which kicks it's tail without the rpm downgrade.
2. At roughly 55% of speed, performance is reduced by about the same amount .... the Noctuas are only marginally better (1C) .... but significantly quieter than the Corsair's at the same speed .... the Phanteks fans top them both.
http://www.silentpcreview.com/article1345-page7.html
and the same fan at x% of speed gives x% of the performance
http://martinsliquidlab.org/2012/04/15/alphacool-nexxxos-xt45-360-radiator/4/
UT60 goes from 326 watts at 2200 rpm to 210 (65%) at 1400 rpm (64%)