ArchitectureThe architecture is no different from the Ryzen 9 3950X or any other "Matisse," so you can click on the button below to read about it, or skip that section if you're familiar with it.
Architectural Innovations Specific to Ryzen 3 3300X and 3100Both the Ryzen 3 3300X and Ryzen 3 3100 are 4-core/8-thread parts, but their segmentation goes beyond clock speeds to justify the 20% price gap between them. AMD tapped into the multi-core topology of its "Zen 2" microarchitecture to obtain the 4-core configuration differently between the two SKUs. Each 7 nm "Zen 2" chiplet (CCD) physically features eight CPU cores spread across two CCX (compute complexes) with four cores and 16 MB of L3 cache, each. For the 8-core Ryzen 7 parts, all eight cores are enabled. For the 6-core Ryzen 5 and 12-core dual-chiplet Ryzen 9 3900X, one core per CCX is disabled, yielding a 3+3 core CCX configuration.
The Ryzen 3 3300X and 3100 are designed differently at the CCX-level. For the entry-level 3100, AMD disabled two cores per CCX and reduced the L3 cache amount to 8 MB per CCX. This 2+2 core CCX configuration with 16 MB of L3 cache (2x 8 MB) still qualifies AMD's specs sheet. The 3300X has a key difference. One of the two CCX on the chiplet is completely disabled, and all four cores are localized to a single CCX, with its full 16 MB L3 cache enabled and shared between all four cores. This improves inter-core latency and lets a core access >8 MB of L3 cache if it wants. For the Ryzen 3 3100, inter-core communication between CCXs comes with certain performance costs arising from latency.
AMD B550 ChipsetWith premium AMD X570 chipset-based motherboards starting at $150, it's less likely that someone would pair the 3rd gen Ryzen 3 with it. Choosing a cheaper B450 motherboard would mean giving up on killer features such as PCIe gen 4.0. AMD hence launched the new B550 mid-range chipset alongside these processors. Motherboards based on the new chipset are expected to be available around mid June, 2020, at starting prices similar to B450-based ones. The B550 chipset lets you have PCI-Express gen 4.0 connectivity from the "Matisse" processor, while limiting general purpose PCIe downstream connectivity to gen 3.0.
On a typical B550 chipset motherboard, the main PCI-Express x16 slot will be gen 4.0 if paired with a 3rd gen Ryzen "Matisse" processor, as would one of the board's M.2 NVMe slots that's wired to the processor. All other PCIe or M.2 slots which are wired to the B550 chipset will be gen 3.0. This way, future-proofing of the platform for next-generation graphics cards and SSDs remains intact. The B550 chipset provides up to six SATA 6 Gbps ports with AHCI and RAID capability, up to two 10 Gbps USB 3.1 gen 2 ports (in addition to four such ports put out by the "Matisse" processor), two additional USB 3.1 gen 1 ports, and six USB 2.0 ports. The platform's HDA and LPCIO buses are located on the processor.
A word on compatibility: the B550 chipset only supports 3rd gen Ryzen "Matisse" processors as of this writing and AMD confirmed support for next-generation processors based on the "Zen 3" architecture. You cannot pair a B550 motherboard with older Ryzen 2000/1000 processors or even the 3200G or 3400G APUs based on the older "Zen+" microarchitecture. There will be clear labeling on B550 chipset motherboard boxes to this effect.
What we like most about the B550 is its low TDP, which lets motherboard designers make do with passive heatsinks; unlike X570, which requires active fan-heatsinks.