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ASUS PRIME B850M-K motherboard with Ryzen 9 9900X3D CPU installed

ASUS

ASUS PRIME B850M-K & Ryzen 9 9900X3D AMD motherboard combo

SKU CH-BYE8-CV3E9

A motherboard and CPU bundle built around a 12-core Ryzen 9 9900X3D with 128 MB L3 cache, DDR5-8400 support, PCIe 5.0, three M.2 slots and 2.5 Gb Ethernet

  • CPU Socket TypeAM5
  • Ready-to-build combo with Ryzen 9 9900X3D CPU included
  • 12-core processor with 128 MB L3 cache for heavy workloads
  • DDR5 memory support up to 8400 MT/s for fast throughput
  • PCIe 5.0 slot plus three M.2 slots for high-speed expansion
  • 5 Gb Ethernet and USB 10 Gbps Type-A for quick transfers

AM5 motherboard and Ryzen 9 9900X3D combo

This bundle pairs an ASUS PRIME B850M-K motherboard with the AMD Ryzen 9 9900X3D processor. The board uses the AM5 socket and B850 chipset in a micro-ATX layout. The 12-core CPU runs at a 120W TDP and includes 128MB of L3 cache plus integrated Radeon graphics. It targets builders who want a ready-matched platform for gaming or content creation.

Check AM5 cooler clearance and DDR5 memory

Verify that your CPU cooler mounts on the AM5 socket and fits the board's VRM heatsink layout. The platform requires DDR5 modules; the board supports speeds up to 8400 MT/s when overclocked. Ensure your power supply provides the necessary 12V and ATX connectors for the 8+2+1 phase VRM design. Confirm the chassis can accommodate a micro-ATX motherboard with a full-length PCIe 5.0 slot.

Three M.2 heatsinks and 2.5Gb Ethernet included

The motherboard ships with three onboard M.2 heatsinks to keep high-speed storage cool under load. A Realtek 2.5Gb Ethernet controller provides wired networking faster than standard gigabit. Rear I/O includes a USB 10Gbps Type-A port and a Type-C connector for quick peripheral access. UEFI BIOS, Aura Sync lighting control and second-generation addressable ARGB headers let you tune performance and aesthetics.

Highlights

  • Ready-to-build combo with Ryzen 9 9900X3D CPU included
  • 12-core processor with 128 MB L3 cache for heavy workloads
  • DDR5 memory support up to 8400 MT/s for fast throughput
  • PCIe 5.0 slot plus three M.2 slots for high-speed expansion
  • 5 Gb Ethernet and USB 10 Gbps Type-A for quick transfers

Specifications

BrandASUS
ModelPRIME B850M-K+R9 9900X3D
CPU Socket TypeAM5

Questions about this item

Does the ASUS PRIME B850M-K and Ryzen 9 9900X3D combo include a cooler or must I buy one separately?

The bundle contains the motherboard and the Ryzen 9 9900X3D processor only; a compatible AM5 CPU cooler is not included and must be purchased separately.

Should I pick DDR5 8400 MT/s memory or a lower speed for this board?

The board supports DDR5 up to 8400 MT/s when overclocked; choose a kit rated at that speed if you want the highest official frequency, otherwise any DDR5 kit will run at its rated JEDEC speed.

What does the 128 MB L3 cache on the Ryzen 9 9900X3D actually do for gaming?

The large 128 MB L3 cache reduces latency for frequently used game data, letting the 12-core processor keep more instructions on-chip and improving frame rates in cache-sensitive titles.

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