Xeon E5 cpu work in low status

[李森]

hi,all:
        the cpu of my machine is :  Intel(R) Xeon(R) CPU E5-2643 0 @
3.30GHz.

        after a reboot. The cpu freq is : sysctl dev.cpu.0.freq
dev.cpu.0.freq: 1200

        i didn't set any power savings config in rc.conf.

        How can i fix this?