if you have anything you can do with the clocks I would definitely start by looking in the frequency/voltage control tab for an adjustable frequency, base clock or voltage.
Are you experienced at overclocking at all? Not trying to sound condescending, just want to know if we need to start at basics or not.
There are other values you will have to change before changing your frequencies and voltages if you find that you can overclock in bios.
Report back with what you find and we can go from there.