Beta testers started receiving Steam machine prototypes from Valve last week. Photos and unboxing videos have already made the rounds, but I think this is the first time we've see a full teardown of the system. Of course, the teardown is the work of the very talented folks at iFixit.
I won't spoil too much of the article, but in a nutshell, the Steam machine prototype is an off-the-shelf Mini-ITX PC built inside a cleverly customized enclosure. To achieve the flat, set-top-box-style form factor, Valve used a low-profile Zalman cooler and a PCI Express riser. The riser allows the graphics card—a Zotac GeForce GTX 780—to lie on its side next to the motherboard, taking no extra vertical space. Valve also used a small-form-factor SFX power supply in order to keep the system compact.
The most interesting part of the Steam machine prototype is probably what iFixit calls the inner cowling: a set of plastic frames designed to wall off heat-generating components from one another. The processor, power supply, and graphics card all seem to get their airflow from vents directly facing their respective fans, and thanks to the cowling pieces, those parts shouldn't heat up adjacent components much at all. That's a pretty clever way to avoid overheating and excessive noise levels in a system this cramped—and with components this fast.
Other than that, there's nothing terribly remarkable about the Steam machine prototype. iFixit gives it a 9/10 score for easy repairability. We still don't know if that exact configuration and enclosure design will make it to the market, but either way, the attention to detail and modularity of components bodes well for retail Steam machines.