BIOS of Veriton M2631 - Isn't it possible to reduce the fan speed of low spinning fans?

Hello,

I have bought a Veriton M2631 and connected a Scythe SU1225FD12L-CDP (300 ~ 800 rpm) for the cooler because I want a very silent PC. I thought it would run at the lowest possible speed when I enable the fan-control in the BIOS. But it runs with the highest speed (ca. 800 rpm)! (Don't laugh, but it is too loud for me.) A smaller fan that I tried ran with ~5000 rpm without fan-control and with 800 rpm with fan-control enabled. Does it mean that the BIOS determines the revolutions but not the voltage, and therefore it it useless to use low-speed-fans? I am a little bit disappointed because I expected something completely different…

Would it be possible for a programmer to change the value in the BIOS? (A BIOS-Update did not change it.) I don't know if there is a solution beside using low-noise-adaptors, but I am still hoping…