AMD’s X3D-series Ryzen processors are a hit with PC gamers and system builders, and it’s easy to see why. These CPUs have a dramatic effect on game performance thanks to some extra 3D V-cache, a sort of “special sauce” design that boosts the pushing of polygons. You’ll see them on sale from time to time, and right now you can take off a whopping $200 on the AMD Ryzen 9 7900X3D, bringing its retail price down to just $397.77 at Amazon. The Ryzen 9 7900X3D is the second-fastest CPU of its generation, with 12 cores maxing out at 5.6GHz. More importantly, it uses double the L3 cache (compared to i…