You can try to raise the fsb clock and that will indirectly raise the ram clock as well even if it were not working on a 1:1 ratio to the NB and cpu FSB. That will overclock your cpu though but it should be to much. The gains from 1066 to 1333 are small knowing that most of the bandwidth is wasted by the memory controller's poor overall performance for the 775 platform.
Go through the guides. Then take your core voltage off Auto and set your memory voltage to factory recommended values You can push the DDR3 voltage to 1.65 volts in a Core2 system. Change the System Memory Multiplier from AUTO to 4.0. Then when you increase the FSB, the memory clock will rise in in proportion with it. At an FSB of 266 MHz, your memory clock should be at 1066 MHz. At an FSB of 333 MHz, your memory clock should be at 1333 MHz.
Download CPU-Z to check your FSB:RAM ratio. It should be a 1:1 ratio.