I recommend you not to go for a fanless PSU. They are more expensive and fail more often due at least partly to user misunderstanding about cooling requirements. In this case, the SILVERSTONE nightjar 450W (by Etasis Electronics) is a great fanless PSU that requires an internal case air temperature of 25°C (or less) to work properly (so you will need a good air circulation inside your case).
On the other hand, a 230VAC line voltage is needed to deliver 450W DC output.
Take in mind that residual noise from the other components in the system may erase the noise advantage (case fans, cpu fan, HD, ...).
I would go for a Nexus Value 430 (by Hipower) (80$ in Newegg) if you want silence for a few bucks. The quality of this PSU is decent enough.
But if you want a high quality and very quiet PSU I recommend you to go for a ANTEC SIGNATURE 650W (by Delta Electronics) or a SEASONIC X-650. They are impressive PSUs which work extremely quiet. You will have an excellent PSU running quietly for a very long time.
My cpu will have a fanless cpu, fanless gpu and an SSD and the case has no side panels. There will be no fans in the system. Therefore no noise. I can go with a quiet psu.
My Antec EarthWatts 500W is pretty quiet. Mine is the old model (EA-500) which was made by Seasonic. Anyway, I had the oportunity to test a month ago the new EarthWatts 500W (EA-500D) which is made by Delta Electronics, and it's very quiet too. My overall impresion was that the new Delta model performs even better than the old one. Anyway, the final level of noise depends on the load of the system.
The Earthwatts 650W (EA-650) is a very good PSU with an incredible price/performance ratio (85$ newegg). It presents a really quiet 120mm fan. It's an ADDA AD1212HB-A71GL which is rated at 0.37A at 12v and is capable of moving 85.2 cfm generating up to 39 dBA at its maximun speed (2200RPM). It's the same quality fan that comes with the Corsair HX series (520, 620 and 650) and the TX650 PSUs (all of them are made by Seasonic).
It has a good efficiency (80 Plus certification), very good voltage stability (voltages very close to their nominal values) and good ripple and noise supression on its outputs.
Unfortunately, it's not a modular unit, but if you take in mind the price...
In summary, it's a quality PSU which performs quiet, although is not the quietest PSU in the market (the Antec Signature is one of the very best PSU you can buy if you want silence).
On the other hand, as I wrote in the last post, you CAN'T run a fanless PSU in a fanless case. That is not possible. You need a decent airflow inside the case to remove the hot air from inside the case. There are some internal components in a computer (cpu, mobo, HDs,...) generating heat and you must to take it out from the case. If not, the heat builds up inside the case increasing the temperature. Take in mind that the SILVERSTONE nitjar requires an internal case air temperature of 25°C (or less)...If you live in Alaska or Russia, go ahead, but if it's not your case, install, at less, one exhaust fan in your case (an intake fan would be recommended, but it's not necessary).
Anyway, this is just my opinion.