Intel's Extreme X7800 might look like just another inexplicable random model number on the sprawling Core 2 roadmap, but this one's important, because it goes in laptops.
The 2.6GHz CPU comes with a 4MB L2 cache, 800MHz bus and  gamers start your engines  the standard power-friendly dynamic speed adjustment isn't present. This means you get all the performance, all the time, and can overclock it.
Overclocking laptops is like putting rocket fuel in a Ford Fiesta, but hell, it's your life.
source:Wired Blogs: Gadget Lab
Intel announces Extreme mobile CPU
Mobile gaming just got sweeter: Today Intel announced the Core 2 Extreme X7800, its first laptop CPU under the Extreme Edition brand. The 2.6GHz dual-core processor features 4MB of L2 cache and an 800MHz front-side bus, making it the highest-end chip in Intel's mobile lineup. Of greater interest to gamers, though, is the fact that the chip's overspeed protection has been removed, meaning laptop manufacturers and users will be able to overclock the X7800 for even more performance (Intel, of course, denies any responsibility for the consequences of overclocking).
Intel Core 2 Extreme
Now available to go
Like Intel's other mobile product offerings, the Core 2 Extreme X7800 includes such power-saving features as a dynamic front-side bus, which lets the system drop into a "low-frequency mode" to conserve energy, and Enhanced Deep Sleep, which uses less power when the system is idle. Another feature, Advanced Media Boost, is designed to provide better performance for video editing, music, and photography, signaling Intel's intention to market this chip for mobile workstations and multimedia laptops as well as gaming rigs.
Intel claims the Core 2 Extreme X7800 realizes a 28 percent performance increase over the previous generation of dual-core processors--though that's in comparison to the Core Duo T2600, one of the first mobile dual-core processors released in January 2006. We suspect that the X7800's performance gains will be more modest when compared to the current crop of Core 2 Duo processors on the market. Nevertheless, we're excited to see a gaming-oriented processor for laptops, and we hope that pairing it with dual SLI graphics (like those found on the Alienware Area 51 m9750) will bring true desktop-level gaming performance to the mobile space. Laptops built around the X7800 processor will appear on the market in two weeks, and you'd better start saving your pennies: the processor alone costs $851 ($300 more than the current top-of-the-line Core 2 Duo CPU).
source::Intel announces Extreme mobile CPU | Crave : The gadget blog