ASUS AMD B550 搭載 AM4 対応マザーボード PRIME B550M-A【MicroATX】

This article covers ASUS AMD B550 搭載 AM4 対応 マザーボード PRIME B550M-A【MicroATX】.

Overview

The ASUS PRIME B550M-A is a MicroATX motherboard built on the AMD B550 chipset, featuring the AM4 socket for 3rd Gen AMD Ryzen processors. It includes one PCIe 4.0 x16 slot for high-bandwidth graphics cards and dual M.2 slots (one PCIe 4.0, one PCIe 3.0) for fast NVMe storage. With four DDR4 DIMM slots supporting up to 128GB and overclocking up to 4400MHz, it offers solid memory flexibility. Positioned as an entry-level to mid-range solution, this board delivers excellent value for budget-conscious builders who still want access to modern interfaces like PCIe 4.0. ASUS includes Aura Sync RGB support, VRM heatsinks, and Fan Xpert 2+ for thermal management. It's a reliable foundation for a cost-effective Ryzen desktop.

Compatibility Guide

CPU socket: AM4, compatible with Ryzen 3000/4000/5000 series (check BIOS version for support). Memory: DDR4, 4 slots, max 128GB, OC up to 4400MHz. Form factor: MicroATX (24.4cm x 24.4cm), fits most MicroATX cases. Expansion: 1x PCIe 4.0 x16, 2x PCIe 3.0 x1. Single GPU only. Storage: 4x SATA 6Gb/s, 2x M.2 (1x PCIe 4.0, 1x PCIe 3.0). Power: 24-pin ATX main, 8-pin CPU auxiliary. Recommended PSU: 450W+ depending on CPU/GPU.

Product Info

Released in June 2020, the ASUS PRIME B550M-A is an entry-level B550 motherboard with a typical street price around ¥8,500. It carries a standard 3-year manufacturer warranty and is widely available through and major retailers. Market positioning: entry-tier, but with PCIe 4.0 support and dual M.2 slots that are often found on higher-end boards. It's ideal for users who want modern features without overspending.

Best Use Cases

Budget gaming builds pairing with Ryzen 5 5600X or Ryzen 7 5700X for excellent price-to-performance. Office or light creative workstations requiring a compact MicroATX form factor with reliable expansion. Future-proofing with PCIe 4.0 support for next-gen SSDs and GPUs while keeping initial costs low.

Things to Consider

Only one PCIe 4.0 x16 slot; multi-GPU setups (SLI/CrossFire) are not supported. The second M.2 slot runs at PCIe 3.0, so you cannot run two PCIe 4.0 SSDs at full speed. No onboard Wi-Fi or Bluetooth; a separate adapter is needed for wireless connectivity. Audio codec is entry-level Realtek ALC887/897; audiophiles may want an external DAC. Lacks BIOS Flashback; updating BIOS may require a compatible CPU installed.