they revealed the early specs for these machines, and they’re pretty hefty.
The 300 prototype units will ship with the following components:
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
A number of vendors will have available Steam Machines when they release next year, but I’d guess this is considered the “better” or “best” model.