The G31/G41 chipset is an economy, entry level chipset. Unless you get really lucky, you will not be able to push the FSB freq past about 360 MHz. I have a G'byte G41 board. FSB freq of 352 MHz works. 353 MHz doesn't.
Go through the guides. Then take your core voltage off Auto and set your memory voltage to factory recommended values. Change the System Memory Multiplier (or whatever your BIOS calls it) from AUTO to 2.00, 2.00B, or 2.00D - whichever you need to set the Memory Frequency to twice the FSB. Then when you increase the FSB, the memory clock will rise in in proportion with it. At an FSB of 200 MHz, your memory clock should be at 400 MHz. Because you probably will not be able to push your FSB freq past 360 MHz, your max memory clock will be about 720 MHz at a 1:1 FSB:RAM ratio. your value RAM will have no trouble working at those frequencies.