Yeah, thanks a lot for your tests!!! But I arrived at the conclusion that a mini-ITX gaming system is the best solution. What's the point to have an external screen/GPU/PSU/Motherboard (close to)/housing ? At the end the only part of the laptop you'll use is the memory and the CPU. I was interested by the challenge, but now I'm about using my MBPr (late 2013) for lightroom/web/movie/... under OSX. And a Mini-ITX for gaming under Win8.1. A big NAS would be the only "cross hardware" between the two, for data accessibility.