When you overclock the FSB, usually the RAM frequency will follow suit... at 320MHz, the RAM frequency required will be at least 640MHz and usually achieveable using 1:2 memory ratio with DDR2-667. However to run at 1:1 ratios, would require RAM frequencies around 1280MHz (quad pumped) which is way beyond normal RAM clocks. Thus you have to beware of the memory frequency or host/memory settings also when overclocking. Anyway ideal overclocks for Q6600 (without resorting to "odd" frequencies) are...

2.67GHz = 8.0 x 333MHz (min DDR2-667)
3.0GHz = 9.0 x 333MHz (min DDR2-667)
3.2GHz = 8.0 x 400MHz (min DDR2-800)
3.6GHz = 9.0 x 400MHz (min DDR2-800)

Anyway, try inquiring at the overclocking section... moving this thread there..

Still can't overclock? Most of my friends can hit 2.8GHz..3GHz with stock HSF and up 3.2GHz and higher with better HSF, easy peasy..

Just wondering, can specify your full hardware specifications? Like to know about the motherboard and PSU...