First, take off the Auto voltage and Memory settings. Your memory settings are going so high because you are inadvertently overclocking your RAM.
Second, you should be able to reach 3.0 GHz with little or no voltage increase.
At stock settings, your FSB freq should be 266 MHz and your memory clock should be set to 533 MHz. I am not familiar with your BIOS so I cannot tell you how to do this.
After you do that, when your FSB freq is 3.0 GHz (333 MHz X 9), your memory clock should be at 667 MHz.
The G31/G41 chipsets are economy, entry level chipsets. More than likely, you will not be able to push the FSB past about 350 - 360 MHz.