You could try sourcing a selection of games from over the past 5-10 years, and charting their stated minimum and recommended requirements.
More tellingly, compare requirements for games from a given time period with requirements for business apps and operating systems from the same time period. But don't forget about high-end applications like video editors and whatnot. They've been around for quite a while and have pushed the edge, too.
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Bitt Faulk