These will not run without this wire connected to power. Also, while labeled PWM, these fans actually use varying voltage along a 4th wire to control them, not a PWM signal. Weird fans they are.
Mostly, but these fans cannot run off of a normal pwm signal.
Connect the PWM labeled wire to the + wire and call it a 3-pin fan. Works for me, fully variable speed.
The PWM wire does not work the same way a standard yellow PWM wire on most fans/PWM header pin on mobo's.
I had to sacrifice one but I did get it to work, thank you. Hopefully this thread will save anyone from sacrificing more of these cute fans in the future to find out how to power them ;)
PS- These are loud as ****.