Without reading through any deep reports, I have a feeling that Nvidia builds this device, because none of the big 3 manufacturers bought their tech for the next generation of gaming consoles.
And going for the handheld market with a at least similar formfactor like the Vita does not seem like a good idea to me.
I just made my first doom-thread regarding the Steambox. http://gamrconnect.vgchartz.com/thread.php?id=152371&page=1#
Maybe my 2nd doom-thread comes much faster than I thought.
Imagine not having GamePass on your console...