It should be tough to ignore, given that it's monkeying with the duty cycle of the fan's power input. Do you have a way to measure it? Hm... I've never measured a PWM signal with a multimeter - I've always either just plugged into a PWM-capable board or wired up a voltage divider (mostly just a pot -> ground, as the fan has a voltage source if it runs with the PWM disconnected). Beyond playing with the little resistor pigtails that come with various PC fans, I've never tried to control f