Late last year Intel released the Q6700, their brand new baby that was a Core 2 Quad (not duo) and had a clock speed of 2.66 GHz. So what is the difference between the Q6700 and the brand new Q6600, well, other than 100, there is a difference in clock speed of .26Ghz. The new Q6600 runs at 2.4Ghz intsead of 2.66. Also, the Q6600 is locked, meaning there is no option of overclocking this quad core monster.
The talk that quad cores are essentially two duos placed on the same chip is true, and the Q6600 is just two Core 2 Duo E6600 cores on a single socket with a pair of 4MB L2 caches and a 1066MHz frontside bus. So other than the locked state of the Q6600 and its clock speed, there is no difference between the two CPUs. So why is this new processor significant? It is really the first quad-core CPU to hit and be aimed at the mainstream market. While no solid price has been released by Intel yet, it will probably be priced a bit under the Q6700′s $999 price point.
Intel Core 2 Quad Q6600 four-core CPU [Reg Hardware]