OC need some assistance

[Alt3r3dBeast]

Im trying to OC my Sapphire radeon 7850 using after burner and the core clock maxes out at 1050mhz and i cant get the voltage to unlock i went into settings and unlocked it there but it still wont let me change anything

 

[Virssagòn]

Idk if this is the right section though.
But I had the same problem with my hd6870, seems like you can't raise the voltage if the brand doesn't have a tool for it or allows you to use such programs.