TechSpot posted a review on the Asus C90S Laptop Barebones

Unlike conventional laptop computers, the C90S is an upgradeable laptop, meaning that the user is free to replace many of its core components including the processor and the graphics card. Possibly even more interesting than this is Asus' choice of platform, not quite the standard for a mobile system.

The Asus C90S is powered by Core 2 desktop processors rather than the 'Merom' mobile variety. That includes support for the 800MHz FSB Allendale models, as well as the 1066MHz FSB Conroe processors. It is possible, then, to configure the C90S with a Core 2 Extreme X6800 processor operating at 2.93GHz if you'd choose to do so, which certainly makes the C90S a very unique laptop, or should we say mobile desktop replacement.

Asus C90S Laptop Barebones Review