Steam Box Specs Revealed

The prototype units will ship with an Intel Core i7-4770, an Intel Core i5-4570, or an unidentified Core i3 CPU. As far as GPUs go, there will be a mix of Nvidia Titan, Nvidia GTX780, Nvidia GTX760, and Nvidia GTX660 models — all with 3GB of GDDR5. All units will ship with 16GB of DDR3-1600 RAM, hybrid 1TB/8GB SSHDs, and a 450w power supply. Impressively, all of this equipment is designed to fit inside a 12-inch x 12.4-inch x 2.9-inch case. Really sleek stuff.
From Extremetech 

So far, this spec sheet seems to make the Steam Box a great gaming computer, but the question keeps floating, how well will Steam OS be made? In Valve's history, they've attempted to create a point of switching to systems that run Ubuntu. Now, according to Valve, Windows games will be played by "streaming". The definition of that to the gaming communities is still unknown, and may involve emulation. Still, how these things will effect sales of the Steam box and its performance isn't yet known.