According to a Valve Engineer, the Steam Machine specs outclass the most common PC configurations. The company relied on its own hardware surveys to choose the system’s components. Even as an entry-level option, Valve claims that 4K/60 fps performance is realistic, despite a memory-limited GPU.
Notebookcheck is an excellent source.
Look at how meticulous their laptop reviews are: they’re so German it hurts. And they’re one of the only ‘oldschool’ written hardware reviewers that’s still alive.