This hierarchy was originally based on the average performance each CPU achieved in our test suite. We have since incorporated new game data into our criteria, but it should be known that any specific title will likely perform differently depending on its unique programming. Some games, for example, will be severely graphics subsystem-limited, while others may react positively to more CPU cores, larger amounts of on-die cache or even a specific architecture. We don't have access to every CPU on the market, so some of the placements are based on the results similar models deliver. Indeed, this hierarchy chart is useful as a general guideline, but certainly not as a one-size-fits-all CPU comparison resource. For that, we recommend you check out our CPU Performance Charts.
Perhaps you noticed that we split the former top tier in half, moving a handful of quad-module AMD CPUs up in the process. AMD's Ryzen processors are a significant jump forward from the FX processors. Recognizing that a lot of older platforms are going to be paired with graphics subsystems multiple generations old, we wanted to define the top of our range to encourage balance between host processing and complementary GPUs. At this point, anyone with a Sandy Bridge-based Core i7 would realize a gain from stepping up to Coffee Lake or Kaby Lake, for example. And putting AMD's top FX CPUs next to a handful of Core i7s and those older Core i5s represents an upgrade to their status.
Currently, our hierarchy consists of 13 total tiers. The bottom half of the chart is largely outdated; you'll notice those CPUs dragging down performance in the latest games, regardless of the graphics card installed in your PC. If you own a CPU in that range, an upgrade could really take your gaming experience to another level.
Really, it's the top five tiers or so that remain viable. And in that top half of the chart, an upgrade is typically worthwhile if it's a least a couple of tiers higher. Otherwise, there's just not enough improvement to warrant the expense of a fresh CPU, motherboard and memory (not to mention the graphics card and storage solution you'd be considering as well).