Hai Kliton x64, i actually am not familiar wit AMD ( i used to OC Intel ). But since I see the bios menu from your picts, it looks almost identic to intel mobo i ever had. So here i try to give you some clues - not the best ones - on how you can start from.
1st. Make sure how good your cpu cooler. ( at least never use stock cooler when ocing ).
2nd. Make sure what is actual default voltage of your default clock 3 ghz by stressing it with PRIME95 or IBT.
To see your voltage during stressing, open CPUZ or HWmonitor ( last version better ).
3rd. Once you get default vcore / voltage core from cpuz, then go to bios and set System Voltage Control to manual. Start lowering vcore one increment / a notch, save the bios.
4th. Let's see if the cpu can boot to windows.
5th. If it does, then lowering vcore until you find it unstable ( crash / can't boot ). From here you'll know the stable vcore for your default clock.
It's more "trial error", so carry on some experiments.
Remember keeping your eyes on cpu temp while stressing ( use Coretemp or Realtemp or HW Monitor ).
Hoping this helps you a bit.