you'll probably need upwards of 1.5 - 1.55V or more. Change the System Memory Multiplier from the current AUTO (reflects a 2:3 FSB : DRAM ratio, or a 3.0 DRAM multiplier) to 2.5 or 2.66, for an effective 1000 - 1064MHz DRAM frequency at a FSB of 400MHz. Then bump the Vcore to 1.5V, run Memtest at that DRAM frequency and clock, and finally Prime for stability. Like Doc mentioned, 3.5GHz out of a Q6600 is already a decent clock, especially w/ a chip having that high a VID. Once the Vcore hits over 1.5V w/ a 65nm quad, unless your cooling is exceptional (or case temp. is extremely low), the Distance to TJ Max will be much lower than what it should be.