Carte mère MSI PRO B840M-B AMD B840 socket AM5 micro ATX

The MSI PRO B840M-B is a micro ATX motherboard with the AMD B840 chipset and Socket AM5, compatible with AMD Ryzen 7000, 8000 and 9000 series desktop processors. It supports DDR5 memory in dual-channel configuration up to 128 GB and offers multiple storage options including Lightning Gen 4 x4 M.2 and SATA III for HDDs and SSDs. The board features a Direct 7+2+1 digital power design with an 8-pin CPU connector, an optimized chipset heatsink for quieter operation and dust reduction, and a 2.5 Gigabit Ethernet interface for high-bandwidth, low-latency networking.

Advantages

The PRO B840M-B provides stable power delivery through a 7+2+1 VRM phase layout and P-PAK components to sustain heavy workloads. Support for DDR5-8000+ (OC), a 6-layer PCB with 2oz thickened copper, and Core Boost and Memory Boost technologies improve overall performance. Quick-install features such as EZ M.2 Clip II and EZ PCIe Clip II simplify assembly. Integrated audio codecs and PCIe 4.0 expansion ensure broad compatibility for professional and multimedia use.

Suitable for

• Compact professional workstations requiring reliable multi-core CPU performance
• Home or office PCs with high-speed networking needs (2.5G LAN)
• Builders wanting DDR5 support and PCIe 4.0 storage for fast boot and load times

Key specifications

• Chipset: AMD B840
• CPU support: AMD Ryzen 7000 / 8000 / 9000 Series (Socket AM5)
• Memory: DDR5, 2 DIMM, dual channel, up to 128 GB, DDR5-8000+ (OC)
• Form factor: Micro ATX
• Power design: Direct 7+2+1 digital power phases, 8-pin CPU power connector
• Storage: Lightning Gen 4 x4 M.2, M.2 slots and SATA III ports, up to 6 storage drives supported
• LAN: 2.5 Gigabit Ethernet
• Audio: Realtek ALC897, 7.1 channels
• BIOS: UEFI AMI 256 Mbit, ACPI 6.5

How to use

Install the motherboard into a compatible micro ATX case and connect an AM5-compatible Ryzen processor. Populate up to two DDR5 DIMMs following the motherboard manual for optimal dual-channel operation. Connect the 8-pin CPU power cable from a compatible PSU and attach storage devices to the M.2 slots and SATA III ports as needed. Use the EZ M.2 Clip II and EZ PCIe Clip II to secure expansion devices without screws. After assembly, enter the UEFI BIOS to configure memory profiles, storage boot order and network settings.

Recommendations

For stable operation under sustained loads, use a quality PSU with the required 8-pin CPU connector, install adequate cooling for the CPU and chassis, and update the BIOS to the latest version before first use. Enable memory XMP/EXPO profiles in BIOS only after confirming memory compatibility.