Read the Overclocking Guide
I find that G31/G41 boards seem to run out of steam at around ~350MHz FSB. Try increasing the FSB in small increments to see where it begins to fail. Also remember to look at voltages, and make sure the CPU Core Voltage isn't set to auto. It might also help to set the PCIE clock to 100MHz instead of auto.
As for the RAM, try setting it to one of the other 4.00 options. Gigabyte boards will tell you what the memory speed will be before you save the settings. You might have to play around with the RAM timings though.