Slowing CPU fan down

[GTdrew]

I have an Asus A7v mobo with a 1 gig TB volcano II heatsink. The cpu fan is spinng at just the right speed to make the case resonate. If i touch my finger to it and slow it down ~300 rpms it stops and my comp runs a lot quiter. Is there any way to do this through the bios or software ??

Thanks
Drew