I installed the two fans today, then experimented with them.
If hooked to the mother board header, they run very quietly at somewhere around 50% of max rpm. If hooked directly to a power cable, they run noticeably loudly at full rpm. Fan speeds are monitored using SpeedFan, but SpeedFan is unable to control the fan speed.
If I disable the smart fan feature in the bios, the CPU fan sounds like at 747 revving for takeoff. However the case fans do not speed up, and continue to maintain a 50% speed, if connected to mb header. This I don't understand?
There doesn't seem to be any way to get the control I want with the hardware I have. I've enabled the smart fan in the bios to keep the CPU fan nice and quiet. I've hooked the fans to the mb, so they're quiet too. As long as temperatures stay cool, I'm good to go.