I recently got a new mobo and case with 4 fans. I connected it all up and everything works ok except the case fans. The front fan LEDs come on but the front fan, side fans, and rear fans don't come on. They're connected to the 3 pin mobo fan connection via a molex. I don't know if it's due to a lack of power via the mobo or something else. The smaller fan from my old case works fine when connected to the mobo.