Odyssey fan controled by Embed controller (EC) which role as initialize the device before system up. The temperatre you saw in bios is detected by EC and the tempertaure sensor place close to the intel CPU which donot have the senser pin. In another word, the temperature not the CPU direct value, maybe 5 degrees centigrade error. What you saw the temperature value in pfsense or others system is feedback by CPU internal, temperature in BIOS screen feedback by EC, fan run or stop according the EC value.
EC detect value (BIOS screen) and fan speed table like this:
mode: Disable, fan state: stop
mode: Normal, fan state: less than 40°C–stop，45-50°C–50%，50-60℃–60%，above 60℃–80%
mode: Positive, fan state: less than 40°C–stop，45-50°C–70%，50-60℃–80%，above 60℃–100%