Even though Valve has delayed the Steam Machines project to 2015, Alienware is pushing ahead with their custom gaming PC offering, revealing the Alpha at E3 2014.
The Alienware Alpha base model will be available for $550, which is very affordable for a full PC positioned against the Xbox One and PlayStation 4, both of which sell for $399. The base model will pack a Haswell-based Intel Core i3 processor, 4 GB of 1600 MHz DDR3 memory, and a custom-built Maxwell-based Nvidia GPU with 2 GB of GDDR5 memory.
The use of a custom graphics core in the Alpha is interesting, as it's unclear whether this is just a typical implementation of an existing Maxwell GPU such as GM107 (found in the GeForce GTX 750 Ti), or whether Nvidia has collaborated to produce something entirely new for this system.
Either way, it appears the GPU is soldered onto the motherboard, as Alienware notes it's not upgradeable. Several components are upgradeable though, including the CPU, memory, and storage, which is a 500 GB hard drive in the base model system.
Like the Xbox One you'll find HDMI in for direct pass-through, plus HDMI out supporting 4K, four USB ports, Ethernet and optical audio out. Custom configurations from Alienware will allow you to add in Wi-Fi 802.11ac, swap out the Core i3 CPU for an i5 or i7, and upgrade to 8 GB of RAM and a 2 TB hard drive.
Software-wise the Alpha will come with Windows 8.1 pre-loaded, as Valve's SteamOS isn't quite ready, with a custom user interface on top similar to Steam's Big Picture mode. It'll also ship with a wireless Xbox 360 controller with a receiver, due to the delay of the Steam Controller.
The Alienware Alpha will be available sometime in the holiday season.