The unofficial 'Steam Box', which was unveiled earlier this year, will ship to pre-order customers around November 15, and be available in stores from November 29.
European dates, prices and availability will be announced at a future date.
Thanks to the addition of a second SSD connector, the console will launch with double the storage capacity, giving users the chance to potentially boot a second operating system, such as the recently announced SteamOS.
The machine will also ship with a number of pre-loaded "pack-in" titles, although exact details will be announced at a later date.
"The PISTON Console is just Xi3's first step in what we believe will be a transformative technology revolution for the Living Room," explains Xi3 founder Jason A. Sullivan.
"Unfortunately, I can't tell you what I know is coming because it's not time to tell you.
"But I will say this: the bar has been raised. PISTON is smaller, lighter, and will last longer, provide more gaming options and be more powerful than any other gaming console on the planet," he added.
It is powered by a quad-core, 3.2GHz processor, and comes with 8GB of RAM and 128GB of solid-state storage.
It will support the majority of made for PC peripherals, including the Xbox 360 controller.
The machine is believed to have been partly funded by Valve, although the company has since distanced itself from the product.