Hi mates a tiny bottom line, now that i'm done.

Seem to be the vital points for quiet and well cooled high performance are:

1, Fans that correspond great with very efficient cooling devices. With me it was the Prolimatech Genesis blown over by two Prolimatech 140mm red vortex/blue vortex fans. Reconsider your fan connectors on the mainboard on this! Either connect both of them through molex y-cable or have the fan directed towards the backplate of your case y-cabled/potentiometer-sync-controlled for a corresponding 140mm outlet case-fan. This way -given case/vortex fans match in terms of voltage/revolutions- a jamming of hot air inside the case should be prevented.
As interference of fan and cooler design can hardly be tested noise-wise at home and even less so if not all combinations are bought: Google for reviews and test set-ups.

2, No fans smaller than 140mm in diameter nowhere inside your system.

3, A good case (not too expensive, the fractal delfine xl was just about 150$) brings along big, slow-revving fans itself (in 140mm, out 140mm, up and out 200mm) and manages to vent the fans in a manner that won't crush your ears.

4, VidCard fans! Exchange your stock fan for a bigger fan-solution. I picked the Thermalright Shaman coming up with quiet 140mm fan. A review reported a silent 20°C temp decrease at 900rev/min under load.
I use the Asus EAH6970DCII that offers two 120mm fans and a good cooler for its main feature. I consider this superb stock cooler a good roll-back if the Shaman ever should malfunction.
However the price difference was only 15$ to louder singl-fan cards and the dismounting of the stock cooler a piece of cake (4 standard screws to loosen).

The problem are Asus' OC-friendly components on the card's layout: 2 capacitors tangle with 2 heatpipes of the Shaman provoking a smoke-out of your card if carelessly used. The pipes now are bent/hammered upwards a boot to give way for both components. Be careful!
The fan connector is settled down by slot/potentiometer element allowing for quick voltage/rev changes when needed.

5, An oversized semi-passive PSU that gets along without own fan activity as long as possible.


It's done!

Thanx for all your input, guys!

muffinstomp