Go into the BIOS and change either the multiplier (if you can), or the front side bus (should be at 133 now). Raise the voltage (vcore, should be at 1.75, I believe) if it's unstable at higher speeds. Watch your temps, don't want to get too high. At any signs of instability, go back down in speed. Go in small increments so you can find your exact limit.
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