I have successfully overclocked this system to 2.89Ghz, but I can't seem to go any further. I've tried increasing Vcore and NB voltage, but both don't seem to affect stability. OCCT CPU runs for about 5 - 10 minutes than BSOD.
I have the same CPU, mine is at 3.6. You can clock it directly to 3.0 without any voltage adjustment- just change your FSB from 266 to 333 and call it a day. Over that, you are going to have to bump your vcore up until stable at the clocks you want. You can select 9x multiplier or 8x multi...either way works. 8x will allow you OC easier, 9x will get you higher speeds.
Have you read the OC guide? It should give you a good place to start.
I read the guides and they are proving very helpful, however the discrepancy between what I set in BIOS vs. what I see in OCCT is a little curious. I can bump Vcore up and down and it seems like Vcore doesn't change at all.