New Case Fans Don't Spin off Mobo but old fans do?

[Guest]

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.
Any ideas?
Cheers

 

[mikerockett]

More specs? mobo, PSU, case etc

 

[g-unit1111]

What motherboard are you using and what fans do you have connected to it?