Which sensors does Fan Xpert use?

[thompo]

I am using Fan Xpert to control my CPU and case fans. Overall, I think it works good. However, I wonder which temperature this software uses when setting the case fan speed. The AI Suite software only reports two temperatures: CPU and motherboard. Intuitally, one might think that the MB temp is used to control the case fans. However, this temperature stays rather constant at 31-32 C for me. Despite this, case fan #2 (the only one that is pwm-controlled) speeds up to 100% when playing games. According to my profile, it should not reach these speeds below a temperature of 60 C. So my question is this: does Fan Xpert use the readings from some other sensor than the MB, or is case fan #2 going rogue for some other reason?

EDIT: Now, I can answer this question myself. Fan Xpert uses the CPU temp to control the case fans.