You purchased an extreme series CPU without knowing what the point of one is? Well I guess we know how Intel manage to sell any....
As you appear to be at a somewhat beginner level of knowledge (no offence) let me give you enough so that a guide (and my first post in this thread) will make sense to you.
The clock speed of a processor is calculated using the CPU multiplier and the motherboard Front Side Bus (FSB) speed. On first glance this makes no sense because the QX9650 is supposed to work with a 1333 FSB and uses a 9x multiplier.
The reason is that Intel quotes the effective speed, not the actual speed. The actual speed of a 1333 FSB Intel CPU is 333 Mhz. That is because Intel use a "quad-pumped" bus for their processors. If we multiply 333 by 9 you get 2997 Mhz (close enough to 3 Ghz, which is what the QX9650 runs at).
On all CPUs (except for extreme series) the CPU multiplier is locked upwards (but can usually be freely adjusted downwards, indeed this is what Speedstep technology uses to reduce the CPU frequency when the PC idle, to conserve power).
With extreme series CPUs (or "Black Edition" for AMD, with a few notable exceptions such as the X2 6400+), the multipliers are also unlocked upwards. With Intel extreme CPUs you pay a MASSIVE premium for this and for the default clock speed, which is commonly the highest available for that generation of CPUs, at the time of release). If you are not aware, the X in QX indicates that the CPU is part of the extreme series (and the Q indicates a quad core but I'm sure you know this).
So, how do you overclock the CPU when the multiplier is locked upwards? We know the CPU speed is calculated by the multiplier and the Front Side Bus (FSB), so we have no choice but to raise the FSB and overclock the motherboard in the process.
One of the reasons P35 and P45 are very popular overclocking motherboards is that they are able to reach very high Front Side Bus speeds and are not that expensive. It means you can pair a locked-multiplier CPU like the Q9450 and overclock it up to and beyond the QX9650 default clock speed and pay much less for equal performance.
Overclocking using the Front Side Bus has an obvious downside, being that it increases wear and tear on the motherboard components (stress in other words) and requires memory that can cope with the speed increase (the memory frequency must match or exceed the Front Side Bus speed). As it happens memory really doesn't matter, as PC2-6400 and PC2-8500 (plenty enough for overclocking) are inexpensive (note that DDR is quoted as double the actual speed, it is this actual speed that needs to match the actual FSB speed).
What does this mean for you? Absolutely nothing, because the CPU you have purchased has an unlocked multiplier. By raising the multiplier alone you are overclocking only the CPU (so no extra stress for the motherboard, which is great). As far as voltage required for stability it doesn't matter if you use the multiplier method or the FSB method, both are overclocking the CPU and may require (make that will require if you go high enough) extra voltage to stabilise the overclock.
There is one extra point with multiplier versus FSB overclocking and that is raising the FSB (and memory frequency) increase the throughput (or "bandwidth") and will usually bench faster with a CPU at the same frequency but a lower FSB speed. What you choose to do about that is up to you but personally I would just enjoy the unlocked multiplier and either leave the motherboard as it is, or raise the frequency to the maximum your memory supports (if you have PC2-6400, that will be 400 FSB).
I'm not sure what the range of the unlocked multi on the QX9650 is (must be some limit) but even if it is 11 you get 3.6 Ghz with the stock 333 FSB or 4 Ghz with 12.
