chassis fan an mother board problem

[arch3n]

hi. fx6350, xfx7770 ,2x4g 1600 corsair vengence, m5a97 r2 latest bios update, power 750w 85% efficiency.my chassis has 3 fan. it works well and after rebooting the fans malfunction or stop one by one. i unplup each one of the fans and it works again good with two fan. i notice cpu over temp when the system is in the state of malfunction by 10 C. chassis fans are cheap and is its stock. what is the problem ? chassis fans ? motherboard power controller units ? psu ? tnx

 

[Unolocogringo]

Check you bios settings.
You probable have the fan duty set too low. Some fans need 7v or more to start, but after they start they can go down to 5 volt or less. You can set a minimum or 600rpm (example) so that the power to the fans does not drop below a point where they no longer function.