MSI PRO B840M-P WIFI6E Micro-ATX マザーボード MB6807

This article covers MSI PRO B840M-P WIFI6E Micro-ATX マザーボード MB6807.

Overview

The MSI PRO B840M-P WIFI6E is a Micro-ATX motherboard built around the AMD B840 chipset, supporting Socket AM5 processors from the Ryzen 7000, 8000, and 9000 series. Its silver-white heatsinks give it a clean, understated look while providing adequate cooling for the VRM area. It packs two PCIe 4.0 x4 M.2 slots, four DDR5 DIMM slots, and integrated Wi-Fi 6E + 2.5GbE LAN, making it a well-rounded choice for budget-conscious AM5 builders. In the current DIY PC market, entry-level to mid-range AM5 boards have been proliferating. The B840M-P sits firmly in the value segment, offering essential features like DDR5 memory support and fast networking without the premium price tag of X870 or B650 boards. It's a pragmatic option for users who prioritize stability and cost-effectiveness over extreme overclocking or PCIe 5.0 connectivity.

Compatibility Guide

CPU Socket: AM5. Compatible with Ryzen 7000, 8000 (including Ryzen 5 8600G APU), and 9000 series processors. A wide selection from budget Ryzen 5 7500F to flagship Ryzen 9 9950X can be used. Memory: 4x DDR5 UDIMM slots, up to 256GB total, with overclocking support up to DDR5-8000+ and AMD EXPO technology. Dual-channel operation is standard. Expansion Slots: One PCIe 4.0 x16 slot for the graphics card, plus one PCIe 3.0 x1 slot for smaller add-on cards. Note that the x16 slot runs at PCIe 4.0, not 5.0, which is sufficient for current-gen GPUs. Storage: Two M.2 slots (both PCIe 4.0 x4) and four SATA 6Gbps ports. Both M.2 slots support NVMe SSDs; they share bandwidth with SATA ports only when specific SATA ports are used—check the manual. * Networking: Realtek 2.5Gbps Ethernet + Wi-Fi 6E (802.11ax) + Bluetooth 5.3. The wireless module is integrated on the board, saving a PCIe slot.

Product Info

The MSI PRO B840M-P WIFI6E launched alongside the AMD B840 chipset in late 2024. Its market position is firmly entry-to-mid range, with a typical street price of around ¥15,000 (approximately $110 USD). The board carries a 3-year manufacturer warranty. Key specifications: Chipset: AMD B840 Form Factor: Micro-ATX (244×244mm) Memory: 4× DDR5 DIMM, max 256GB, OC to DDR5-8000+ Expansion: 1× PCIe 4.0 x16, 1× PCIe 3.0 x1 M.2: 2× (PCIe 4.0 x4) SATA: 4× SATA 6Gb/s Rear USB: 1× USB 10Gbps Type-C, 1× USB 10Gbps Type-A, 2× USB 5Gbps Type-A, 4× USB 2.0 Front USB: 1× USB 5Gbps Type-C, 2× USB 5Gbps Type-A, 4× USB 2.0 Audio: Realtek ALC897 7.1ch HD Audio LAN: Realtek 2.5GbE, Wi-Fi 6E, Bluetooth 5.3 The B840 chipset is a simplified version of B650, but retains critical capabilities: DDR5, PCIe 4.0, and USB 10Gbps. This board is an excellent foundation for a cost-effective AM5 build that doesn't sacrifice modern memory and storage speeds.

Best Use Cases

First-time AM5 builder on a budget: If you're moving from an older platform (AM4 or LGA1200) and want to keep costs low while enjoying DDR5 and fast M.2 storage, this board is an ideal starting point. However, if you plan to heavily overclock or use multiple PCIe cards, step up to a B650 or X870 board. Compact office or home theater PC: The Micro-ATX size fits easily into smaller cases like the Fractal Design Pop Mini or Cooler Master Q300L. Built-in Wi-Fi eliminates the need for a separate card, keeping the build clean and cable-free. Light gaming system with a mid-range GPU: Paired with a Ryzen 5 7600 and an RTX 4060 or Radeon RX 7600, this board delivers great 1080p/1440p gaming performance. The PCIe 4.0 bandwidth is fully sufficient for those GPUs. Casual content creation: For video editing or photo processing in software like DaVinci Resolve or Lightroom, the combination of fast M.2 storage and DDR5 memory offers good responsiveness. Avoid heavy multi-GPU or PCIe-based accelerator tasks due to limited expansion. ## Alternatives
ASUS PRIME B840M-A WIFI: Similar specs and price. The MSI board includes M.2 heatsinks as standard, while the ASUS board supports BIOS Flashback for CPU-less updates. Choose MSI if storage cooling matters, or ASUS if you need easy BIOS recovery. GIGABYTE B650M D3HP: A step up with the B650 chipset, offering one PCIe 5.0 M.2 slot and slightly better VRM. It costs about ¥3,000–5,000 more. If you plan to use a PCIe 5.0 SSD in the future, the B650 board is worth the extra investment.

Things to Consider

The most notable limitation is the lack of PCIe 5.0 support for both the GPU slot and M.2 slots. While PCIe 4.0 is ample for current graphics cards and SSDs, future high-end hardware may benefit from the extra bandwidth. Additionally, the single PCIe x1 slot severely limits expansion—no room for a capture card, high-end sound card, or extra USB controllers simultaneously. The VRM design is adequate for Ryzen 5 and Ryzen 7 chips, but running a Ryzen 9 under sustained all-core loads may push temperatures higher than ideal; proper case airflow is essential. If your build budget allows an extra ¥5,000–10,0

Product Disclosure (Amazon)

• Manufacturer: MSI
• Seller: Amazon.co.jp
• Fulfilled by: Amazon.co.jp
• ASIN: B096Y53VL8
• Note: This article covers a manufacturer-made product based on Amazon listing details.