Such a device would necessarily need to make some engineering compromises (thermal and layout issues). It would also have a tiny market. As such, the price woul

Such a device would necessarily need to make some engineering compromises (thermal and layout issues). It would also have a tiny market. As such, the price would also be rather high. For example this is pretty much what the Vaio Z was. A very thin and light (17mm, 1.15kg) laptop with a high-res screen (1920*1080), a real CPU (up to quad core mobile i7, not a ULV chip), and a 7670M GPU. There were just two catches: the GPU was housed in the (tiny) external docking station, and the laptop + dock cost something like $3000. Unsurprisingly, it looks like Sony killed the whole external GPU concept in this years refresh.