As I understand it (and I may be totally wrong - please correct me if I am), the Q6700 is essentially an overclocked Q6600, one with a CPU multiplier of 9, the other with one of 10, thus taking the speed from 2.4GHz to 2.66GHz.

Is the same true for the Q9450 and the Q9550? Is there any difference between the two other than CPU multiplier?

lol!

all cpu's of the same familey, are the same - few difference

difference is the miltipler or fsb thats it

6,7,8,9,10

10 = extreme core 2

6 = low cost cpu core 2

9= optimal core 2

11 = too high multipler of the unlocked core 2 but needed if you have low fsb mobo

quad = 2 x qore 2

they turn off features and change the mem cache

q9300 has less the cached then q9450 - hence the 50

9450, 9550, 9650 (new chip soon) are all the same

sometimes you have different stepping or build in programing or instuctions

Q6600 B3 is old Q6600G0 is new

Qx6700 was a b3 a Qx6850 was a G0 - the extemes get it first!


overclocking is tuning - yes the q9550 is a q9450 with a slightly higher multipier raised from 8 to 8.5

Really wrong.
The Q6600 was not quite up to the quality of the Q6700. It got binned lower as a result.
The same is true of the 9450. Intel would rather sell it as a 9550, but it doesn't quite make the grade.

So then, if someone where an overclocker, why would they not just want to buy a Q9450 and OC it to 9550?

Are you referring to factory quality screening that can detect the heat levels a chip is estimated to handle, or something of that nature? The chips are the same in other ways, but one can OC better?

Actually, the binning process also has a lot to do with demand. If the yields are low, then what endyen says is correct, but not everyone can afford the 9550, or wants to pay for it, so there are compromises made. As it happens, the yields are very good on C2Ds and all of the chips are binned to relatively low speeds and voltages, which means we tend to get great overclocking headroom on most of them.

To answer the initial question, though, the Q6700, while pretty much identical to the Q6600 does come with a higher, LOCKED, multiplier. While this isn't such a big issue between the Q6600 and Q6700 because of their low FSB frequency and high multipliers, for the newer 45nm CPUs with higher FSB frequencies (333MHz instead of 266), the multipliers are lower, and so the FSB frequency must be raised considerably to attain the same clockspeed. The Q9450 has a multiplier of 8, while the Q9550 has a multiplier of 8.5. While this may not seem like much, at a fairly typical FSB frequency of 400MHz, the Q9450 will be running at 3200MHz while the Q9550 will be running at 3400MHz, thus making it easier to obtain higher CPU clock frequencies with the higher multiplier when the CPU multiplier and maximum speed of the FSB is the limiting factor. (i.e. any of the CPUs listed here and the P35, X38 or X48 chipsets).