G41 boards don't OC. At least not well.
Stock Q6600 is 2.4GHz on a 1066 FSB for a CPU multiplier of 9. 3GHz / 9 = 333.33FSB. This is possibly doable, though it's going to depend on your board. And your ram. Because as you increase the FSB you are going to increase the RAM speed. And many G41 boards don't have FSB:RAM ratios to pick from.
If none of that made any sense at all, you need to read more. Education on how to OC is going to be your friend. It's not as simple as just picking a value in the bios and running with it.