PWM fan headers influencing one another.
PWM fan headers influencing one another.
It's tough to pinpoint without more context. It seems related to SPEEDFAN or possibly both fans being connected together.
Most motherboards come with their own fan control tools. Do you have any? (Note: I use Windows 10 on my Asus Z77 board, but the fan control software, Thermal Radar, is only listed under the W7 list)