IIRC correctly Steam has a (yearly?) hardware survey which their users have the option to take part in, collecting information about parts in the computer and about connected periphery devices, i.e. model names, no. of monitors, resolution, amount of RAM, ...
And Valve is very transparent about how that works -- the survey displays a detailed opt-in each time the user's data is collected, and the results of the survey are public (https://store.steampowered.com/hwsurvey).
Well the collection part is transparent (so there is no privacy issue) but they don't disclose how and how ofthen they select participants or even how many participants there were for each survey.
