Valve's Greg Coomer has informed anxious gamers regarding what to expect from the 300 prototype Steam Machines the company will be shipping out later this year. The first prototype Steam Machine is a high-end, high-performance box, built out of off-the-shelf PC parts. It is also fully upgradable, allowing any user to swap out the GPU, hard drive, CPU, even the motherboard. Apart from the custom enclosure, anyone can go and build exactly the same machine by shopping for components and assembling it themselves.

Here are the specifications for Valve's 300 prototypes sent to beta testers:

- 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

According to the specs above, there will be some Steam Machines likely priced close to $650-700 (basic H81 motherboard included) while others will probably cost $2000 or more.

Valve's Steam Machines were tipped off more than a week ago, when Valve announced its Steam OS, the Steam Machines, and a related Steam Controller. Steam OS will be Linux-based, and will run a library of games on what Valve is billing as open hardware.

In an interesting twist, all of the Steam Machines use an Intel CPU and an Nvidia-based graphics card, not AMD's CPUs and GPUs. NVIDIA and Valve have been working together on the upcoming SteamOS and Steam Machine prototypes for some time now. According to Mike Sartaina member of the Linux teamValve, "NVIDIA has done a ton of work to optimize its GTX GPU series on Linux. That work applies across the GTX product line, which provides a complementary set of GPUs for our desired range of prototype Machines."

Valve Software's decision to drop support for AMD graphics card comes as PC maker Origin PC also said Friday that it will shift entirely to Nvidia GPUs.

"This decision was based on a combination of many factors including customer experiences, GPU performance/drivers/stability, and requests from our support staff," said Kevin Wasielewski, Origin PC CEO. "Based on our 15+ years of experience building and selling award winning high-performance PCs, we strongly feel the best PC gaming experience is on Nvidia GPUs."

Wasielewski added that he has received interesting feedback from his technical support managers, who claimed that AMD's graphics cards had more stability and overheating issues than Nvidia's. In addition, Nvidia was faster in delivering new drivers on both desktop and mobile GPUs, he said.

On the other hand, Origin continues to sell AMD's CPUs as alternatives to Intel's parts.