You'd be better with a Fractal Define R5 or Antec P180-series, with a couple of large slow fans. These are both heavy-built cases with internal sounds damping and limited noise paths. You should aim to have a single clear airpath from bottom/front to top/rear, with no shortcuts for cold air to leave early or enter late. Have more intake airflow than exhaust to limit dust and fluff.
I'd be interested to measure my machine's db and compare it to the one in your spec. It's hard for me to visualize auralize? the volume difference. Silent is silent though, right? :)
http://www.nofancomputer.com/eng/products/CS-80.php
All those vents aren't going to help much.
You'd be better with a Fractal Define R5 or Antec P180-series, with a couple of large slow fans. These are both heavy-built cases with internal sounds damping and limited noise paths. You should aim to have a single clear airpath from bottom/front to top/rear, with no shortcuts for cold air to leave early or enter late. Have more intake airflow than exhaust to limit dust and fluff.
5 pages of R5-based build guide:
http://www.silentpcreview.com/Quiet_ATX_Gamer_R5_Version