MSI MAG B550M Mortar MAX DDR4 AMD Motherboard

The MSI MAG B550M Mortar MAX DDR4 is a Micro-ATX motherboard built on AMD’s B550 chipset and designed for AMD Ryzen 5000 Series, Ryzen 4000 G-Series, and Ryzen 3000 Series desktop processors using the AM4 socket — note that AMD Ryzen 5 3400G and Ryzen 3 3200G are not supported. The compact 9.6 × 9.6-inch (244 × 244 mm) form factor makes it an excellent choice for space-efficient builds that still demand high-end connectivity and expandability. One of the MAG B550M Mortar MAX’s headline features is its Lightning Gen 4 M.2 slot (M2_1, sourced directly from the AMD processor), which supports PCIe 4.0/3.0 x4 and SATA 6Gb/s, enabling next-generation NVMe storage with up to 64 GB/s theoretical peak bandwidth via PCIe 4.0. A second M.2 slot (M2_2, from the B550 chipset) supports PCIe 3.0 x4 for additional fast storage. Six SATA 6Gb/s ports round out storage options, while RAID 0, 1, and 10 are supported for SATA devices and RAID 0/1 for NVMe drives. Memory support is extensive: four DDR4 DIMM slots accept up to 128 GB of unbuffered DDR4 in dual-channel configuration. JEDEC speeds up to DDR4-3200 are supported natively, while A-XMP overclocking extends support to DDR4-4400+ depending on DIMM configuration. Connectivity is a strong suit. The Realtek RTL8125B controller delivers 2.5 Gbps wired LAN for low-latency networking. On the rear panel you get USB 3.2 Gen 2 10 Gbps Type-A and Type-C ports (both sourced from the AMD processor), USB 3.2 Gen 1 5 Gbps Type-A, and USB 2.0, plus HDMI (up to 4096×2160 @ 24 Hz) and DisplayPort (up to 4096×2160 @ 60 Hz) for APU-based display output. The built-in Flash BIOS Button allows firmware updates without a CPU installed. Audio is handled by a Realtek ALC1200 codec with 7.1-channel HD audio and optical S/PDIF output. For chassis builders, the board includes a front USB 3.2 Gen 1 Type-C internal header, two 3-pin RAINBOW addressable RGB headers and one 4-pin RGB header for lighting customisation, plus fan headers for CPU, water pump, and three system fans. An extended heatsink with 7 W/mK thermal pads and 2oz copper PCB layers assist VRM thermal management under sustained load. The board carries a 3-year manufacturer warranty. Key Verified Specifications: • Chipset: AMD B550 • Socket: AM4 (Ryzen 5000, 4000G, 3000 Series; excludes Ryzen 5 3400G & Ryzen 3 3200G) • Form Factor: Micro-ATX, 9.6 × 9.6 in (244 × 244 mm) • Memory: 4× DDR4 DIMM, up to 128 GB, dual-channel; JEDEC up to DDR4-3200; A-XMP up to DDR4-4400+ • Storage: 2× M.2 (M-Key) — M2_1 PCIe 4.0/3.0 x4 + SATA; M2_2 PCIe 3.0 x4; 6× SATA 6Gb/s • Expansion: 1× PCIe 3.0/4.0 x16, 1× PCIe 3.0 x16 (x4 mode), 2× PCIe 3.0 x1 • LAN: Realtek RTL8125B 2.5 Gbps • USB (rear): 2× USB 3.2 Gen 2 10Gbps (1× Type-A, 1× Type-C), 2× USB 3.2 Gen 1 5Gbps Type-A, 2× USB 2.0 • Audio: Realtek ALC1200, 7.1-channel HD, S/PDIF optical output • Display: 1× HDMI (4K@24Hz), 1× DisplayPort (4K@60Hz) • Multi-GPU: 2-Way AMD CrossFire • OS: Windows 10 64-bit • Warranty: 3 Years