Valve has outlined the specifications of the 300 Steam Machines going out to beta testers later this year.

In a post on the Steam Universe group on Steam, Valve’s Greg Coomer said the company always planned to partner with hardware manufacturers to combine high-end power with a living-room-friendly form factor, all in a box that’s as open as possible.

“The prototype machine is a high-end, high-performance box, built out of off-the-shelf PC parts,” said Coomer.

“It is also fully upgradable, allowing any user to swap out the GPU, hard drive, CPU, even the motherboard if you really want to.

“Apart from the custom enclosure, anyone can go and build exactly the same machine by shopping for components and assembling it themselves.

“And we expect that at least a few people will do just that. (We'll also share the source CAD files for our enclosure, in case people want to replicate it as well.)

Steam Machine prototype specs:

GPU: some units with NVidia Titan, some GTX780, some GTX760, and some GTX660
CPU: some boxes with Intel : i7-4770, some i5-4570, and some i3
RAM: 16GB DDR3-1600 (CPU), 3GB DDR5 (GPU)
Storage: 1TB/8GB Hybrid SSHD
Power Supply: Internal 450w 80Plus Gold
Dimensions: approx. 12 x 12.4 x 2.9 in high

Pictures of the prototype will be available closer to its ship date, said the company.