AlexiTQ wrote:
Is the motherboard increasing the current and/or electric potential when resistance is applied?
No, this is not possible. 12V is the max rated output on the fan headers, it's also the max voltage supplied to the mobo itself; fan header power supply pin feeds off of the 12V supply, either direct connection or via the system's fan controller chip, which at least on high-end motherboards is often able to lower voltage by itself through software control without using in-line resistors.