Valve has assured that the upcoming line of Steam Machines won't exclusively feature Nvidia GPUs. Considering that multiple hardware manufacturers are involved with the initiative, that seems fairly obvious, but the tech specs for the company's prototype raised questions.
Speaking to Forbes, Valve marketing director Doug Lombardi said "Although the graphics hardware that we've selected for the first wave of prototypes is a variety of Nvidia cards, that is not an indication that Steam Machines are Nvidia-only. In 2014, there will be Steam Machines commercially available with graphics hardware made by AMD, Nvidia, and Intel. Valve has worked closely together with all three of these companies on optimizing their hardware for SteamOS, and will continue to do so into the foreseeable future."
For its part, AMD remarked that "[it] is very actively engaged with Valve on these products and campaigns." Even though we're not even in the prototype phase proper yet, I'm curious to see how many Steam Machines there will be next year -- how different customer needs and price points can be addressed without offering an overwhelming amount of systems.