Last week video game developer Valve, the company behind the Steam online marketplace, unveiled its vision of bringing PC gaming to the living room and TVs. This announcement included hardware called “Steam Machines” that would run SteamOS and be controlled with the new Steam Controller.

Along with the announcement, Valve revealed that 300 lucky gamers will get the chance to test out its prototype Steam Machine. Today, Valve revealed a bit more about that beta initiative, including what hardware the machines will come with.

It turns out that the 300 prototypes will not have consistent hardware. Each could be slightly different from another, though all of them are relatively high end gaming PCs (and some will be really high-end gaming PCs). Each will have an Intel processor and an NVidia GPU. They will also come with tons of RAM and a hybrid 1 TB/8 GB SSHD hard drive. The full specs, from the Steam Universe group announcement:

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 GDDR5 (GPU)
Storage: 1TB/8GB Hybrid SSHD
Power Supply: Internal 450w 80Plus Gold
Dimensions: approx. 12 x 12.4 x 2.9 in high

The prototype machines will be fully upgradable, so users who get the GTX660 can pop in their own Titan if they so choose. It also seems that the prototypes will come packed in a relatively thin square box, similar in size to a slightly wider and thicker PlayStation 4. Valve stated that it is not yet ready to post photos of the prototype box, “because they’re not finished enough.”

Valve also emphasized in this announcement that the prototype is not meant to be the only Steam Machine, stating that other manufacturers will release Steam Machines focused on factors such as a low price or a small form factor. Valve will be creating a system to rate the strengths and weaknesses of different Steam Machines, though details on that will come later. Also, for those who already have nice gaming PCs Valve teased that it is working on a streaming solution to bring SteamOS to their living rooms.