Couple of threads on Valve site

A project log for Hydra Multi OS Gaming Console & Controller

This is a game console sized Hydra with a single GPU, running SteamOS, Win7 & Android x86 KitKat. Gameplay & mgmt via modular controller

ericeric 04/05/2015 at 23:350 Comments

Here are some of the questions addressed by the Hydra design. This is what I use to determine the features I want to incorporate, and the issues that need solving.

Integration with Android Device

"Its not a must be, but for the gaming purposes could be nice if Steam OS will have some integration with Android devices."

Mouse and Keyboard Support?

"So, I might get an Alienware Steam Machine and use it as a game console. However, instead of always using a controller, can I also use a keybiard and mouse? This is because I want to play some games with those controls, like Garry's Mod and Surgeon Simulator 2013."

Multi-system Steam Machine?

"TL;DR? If the thought of getting one or more gaming systems out of hardware you might already own isn't interesting to you; don't read this.

For a very long time, I was trying to work out a way to unlock more use out of my system. The basic idea was to use Xen and at least 2 video cards in either SLI or dual-system mode. The difficult part was passing acceptable performance through more than one video card. Until I found this: "

Steam Machines with Windows?

"Can i use a Steam machine like a normal Computer with windows?"