Next stop should be a guide for your particular motherboard. Google is your friend.
Go through the guides. Then go into the BIOS and 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 step with it. If you are at 3.0 GHz (333 MHz X 9), your memory clock should be at 667 MHz.
Download CPU-Z to check your FSB:RAM ratio.
Warning - confusion factor between what the BIOS calls things and what CPUZ calls things. What the BIOS calls "memory frequency" is actually the memory clock. What CPUZ calls "memory frequency" is half the memory clock - DDR2 RAM, remember? It transfers two chunks of data each bus cycle. What you want in CPUZ is a 1:1 FSB:RAM ratio.
And they are pretty large, so they might not fit inside your case.
Keep in mind that these are guides, not cookbooks. YMMV. Because of all the variables, you may not do as well as someone else with a similar system. Or you might do better. ----------
Overclocking since 1978 - Z80 (TRS-80) from 1.77 MHz to 2.01 MHz