|Overclocking AMD CPU's can be a bit complicated because there are so many settings that need to be adjusted...but once you get the hang of it, there's nothing to it.|
Whenever you change the CPU frequency, there's a domino effect on all other frequencies (PCIE, RAM, HT). To compensate, you need to adjust their settings so that they don't increase too much & limit the CPU overclock potential or cause system instability. The PCIE should always be locked at it's default of 100MHz. The RAM & HT buses should be kept reasonably close to their default speeds.
Good move lowering the RAM setting to DDR667. But you also have to lower the K8-NB Ht setting. That *may* allow you to raise the CPU freq even higher to hit the 3.0GHz mark. These charts may help:
What freq is your RAM currently running at...about 385-390MHz? Ideally you want it to run at 400MHz or slightly higher. What's hurting you is the 11.5x CPU multiplier setting. 11 x 270Mz will run the CPU at 2.97GHz with the RAM at approx 412MHz.
But you still need to adress the K8-NB Ht setting. The HT bus is the product of the CPU freq x the HT multiplier. However, it's not always expressed as a multiplier in the BIOS. Many times there are settings given - 200MHz, 400MHz, 600MHz...1800MHz, 2000MHz, etc. If you divide this number by 200MHz (which is the default freq for ALL AMD CPUs), you can come up with the HT multiplier. I believe the default HT speed for your X4 is 1800MHz (aka 3600MHz)? 1800/200 = 9x multiplier. If you don't lower this setting as you increase the CPU freq to say, 270MHz, the HT bus will run at 9 x 270MHz = 2430MHz. That's way too high & can cause system instability. Not only that, but it *may* limit your CPU overclocking potential. If you were to lower the setting to 1400MHz (7x), the HT bus would run at a much more stable 7 x 270MHz = 1890MHz.