I've got the Scythe Shuriken here now, together with an Intel DP35DP motherboard, a Core 2 Duo E8200 and an Enermax Pro 82+ PSU.
The Shuriken 10 cm fan isn't audible till 1200 RPM even at 60 cm, running it alone; at faster speed, only air whoosh from it, no mechanical noise.
At the first startup I was in the BIOS for a look at temperatures and fans speed and I was dazed by the 62° C displayed in the CPU field. Something wrong with the thermal compound? Badly plugged clips?
Having a better look at the temperature fields I noticed that the one reporting 62° was labeled 'CPU thermal margin'....
The thing I had to work on was: the Shuriken fan, PWM controlled, driven by the DP35DP with the E8200 (updated BIOS) rotates around 380 RPM.
I was not able to find any BIOS setting in order to actually change this.
The whole BIOS itself is quite essential, indeed.
Surfing the documentation I found out that CPU fan speed increases only when VERY close to the thermal margin.
Running some load test I noticed that the temperature of the components beside the CPU (voltage regulators, S&N bridges) does rise faster than the processor, having the fan running at that slow speed....
(Of course I made a quick test with fan stopped, having very similar results).
These temperatures were quite high even working with not too heavy load.
To cut a long story short I had to build some regulators.
I used a MJE350 PNP transistor, a 22KOhm potentiometer( not easy to find a miniaturized one here), 1200 Ohm resistor and a capacitor.
Of course I didn't use the PWM wire.
I even built a regulator for the 25 cm case fan, using a NTC thermistor, a couple of transistors, resistors and capacitors, and mounted both them in a PCI slot cover ( the kind partially sticking out of the case, not the flat one...I'll post some pics...).
Now the Shuriken fan is adjusted around 760 RPM, it's unaudible, and the temperatures are low even running continued periods of heavy load.
The 25cm fan runs at minimum speeds till the temperature inside the case is below 30° C and rises close to the maximum speed at 38° C.

( I tested it outside; inside the case I never was over 27° till now, graphic card only)
I also installed a Noctua NF-S12 12 cm fan extracting air at the front of the case for the HDDs.
It comes with rubber bearings (no screws mounting) and an 'adapter cable' with limitator. This included limitator, however, make it turns too slow for my environment, so I replaced its resistor with a lower one.
No way to connect it directly to the front fan socket of the MoBo: it (and any other fan of course) is driven to accelerate and slow down at short regular intervals and I can't find any setting to adjust this behaviour.
I suppose I have to try to contact the support service, now...
I'm curious about the Nexus fans...
About the Enermax 82+ series, I can confirm: Its' VERY quiet.
ADDED:
When I removed the old parts from the Enermax Chakra case, I noticed the Zalman heatsink was VERY clogged with dust. So I had to build a filter for the 25 cm fan, since the case comes with dust filters for the slots at the front of the case, but without filter for the big fan (!). I also installed dust filters at the back.
ADDED PICS: