The 975X chipset in general is not a good overclocker, and you tend to need to pump voltage through it to be able to get a decent overclock. That said, 333MHz is likely to be attainable, but even that may not be possible depending on what voltage adjustments to CPU and NB voltage your board supports. The most I ever pushed on my old 975X board was 280 without being able to raise the voltage on the northbridge, using my E4400.