Hello,
i've put an new Mugen 2 Rev B in an passive configuration on my non-OC system and i'm very impressed of the quality of the cooler!
Installation is a little bit tricky but almost perfect.
I've used the scythe slipstram as the back-fan of my case (Antec Threehundred) and a Noctua Ultrasilent 140 mm as an additional top-fan. The mugen itself is fanless. The i7-860 on the GA-55-UD5 board gives me after 1 hour in idle mode 29 degrees celsius. Both fans, controlled by speedfan 3.0, were running with about 650 upm.
After one hour with intelburn-test program with 8 threads i've got about 60-62 degrees. Room temperature was 21 degrees. Both were running at about 750 upm not been heard.
Absolutly perfect combination for an non-overclocked but silent system.
The graphic-card is an passive cooled type (i'm not a heavy gamer).