[After a discussion with Andrew Su, this post has been updated to include information on how to set the temperature sensor that controls the fan speed.]
I run a home server built around the Intel S1200V3RP motherboard. To minimize noise levels, it is housed inside a Fractal Design Define Mini case, driven by three Scythe Slip Stream 120 PWM case fans and a Noctua NH-U12S CPU fan.
Contrary to typical desktop motherboards, the BIOS of this server board doesn’t provide functionality to set a curve for temperature versus fan speed. Intel expects its customers to house the board inside an approved chassis, and provides IPMI sensor data records (SDRs) with pre-defined curves for those chassis. For “other” chassis, Intel also provides three generic SDRs called slow, medium and fast ramp. Here are the steps to choose which temperature sensor controls the fans, and how to modify the fan speed and temperature points of the “slow ramp” curve.