The 'world's fastest gaming CPU', according to AMD, is on sale in the US today. The Ryzen 7 5800X3D is down from $450 to $375 via Antonline's Ebay store, an awesome price for an extremely quick eight-core and 16-thread processor blessed with AMD's new stacked L3 cache design, which allows it to beat almost every current-gen CPU in gaming performance.
So how does the 5800X3D work? This gets pretty nerdy, but: basically, it nearly triples the size of the processor's L3 cache compared to the older 5800X, vertically stacking the required circuitry to reach a substantially higher capacity than was possible before.
This L3 cache is used a bit like RAM, in that it's a space for the CPU to keep data it's working on that's way, way faster to access than even a fast SSD. The difference between L3 cache and RAM is that this space is inside the CPU, rather than attached to the motherboard, so you have an order of magnitude less space for your data - but the CPU can also access it an order of magnitude quicker.
Having a larger L3 cache, as in AMD's 3D design on the 5800X3D, means that the CPU spends less time waiting for data, and you can do a ton more processing in the same amount of time. That increases game frame-rates substantially in situations where you're CPU-limited rather than GPU-limited - for example, when running games at 1080p resolution and at very high frame-rates.
The ultimate upshot of all of this is that the 5800X3D is massively faster than the original 5800X in most games, despite running at a slightly lower clock frequency. In testing for Eurogamer, I found it's often not even close - the 5800X3D is 30%+ faster than the 5800X in games like Cyberpunk 2077, Flight Sim 2020 and Hitman 3, and often outperforms the significantly pricier 12900K - even though we tested that CPU with faster (and more expensive) DDR5 RAM.
It's an awesome achievement from AMD to deliver such a great performer at the twilight of the AM4 platform's lifetime, and if you've got one of their B550 or X570 motherboards, this is likely the very fastest CPU will ever be able to buy for it. So - if you're in the market, picking it up for $375 sounds like a pretty good deal to me!