For CPU temps at 4Ghz, I'm not 100% sure that one or two Nexus fans (even at 12V) will be able to cope. A 44C rise
(over 20-21C) ambient with dual Nexus fans at 12V with a 3.6 GHz / 1.4V CPU might translate to temperatures a bit higher at 4Ghz. You might want a bit more headroom for the fans - something like 2 x Scythe Gentle Typhoons might be more suited.
I'm also not so sure about that case and PSU combo. There will be a lot of holes for noise to leak out of and I'm not sure how quiet that PSU is.
If you want to go all out I'd suggest something like the Seasonic X650 PSU. Other than your OC'd CPU, the rest of your system is pretty low power, so that should be enough watts. Otherwise, look at the Recommended PSU list on the main part of the site.
Case wise, you need something that promotes good airflow towards the CPU. You could get a case that has a top fan and turn it around to blow fresh intake air at your CPU cooler. The Silverstone FT-01 is designed to work that way. An Antec P183 with the top exhaust fan reversed might also work.
The Silverstone FT-02 works on a different principle but may also suit your needs.
All three cases have been reviewed by SPCR, so check the reviews out via the main page. Just make sure to suspend your HDD somewhere and you should have a pretty quiet system.