The Brazos cannot be overclocked as far as I know. There is a tool called "Brazos Tweaker" that can change the clocks but the speed won't increase over the maximum no matter what the clocks are set to. It is not a good idea to increase the clock without additional cooling anyway, For every 7 degrees C the temperature increases the remaining life expectancy of a semiconductor is cut in half.
There are, however. a couple of things that you can do to increase speed. Make sure that Windows is set for performance. Then confirm in the Vision Control Center under hardware that the memory bandwidth reported is the same as the installed module. If it isn't then you could try updating the BIOS and tell it to set optimum configuration.
After that, if the memory slot is still open, adding another memory module on the same channel should increase the sustained average bandwidth by about 20%.