now i switched the fan yate loon fan from the psu (D12BL-12, a 45 cfm/ 76 m^2/h fan) with a case fan from the fractal design mini (40,6 cfm). i was a bit suprised when it actualy worked without hooking a fan up to the fan conector in the psu as i conected it to the 12v line outside of the psu.
I'm not familiar with this PSU but does it offer any fan speed control? Even pretty basic PSUs have it so I would expect so. If you can rewire the Fractal design fan to connect to the PSU fan header then you will get it running silently under low loads.
If your system uses as little power as it does then you'd also probably be OK with a 500rpm fan in the PSU as you simply won't be heating it up much.