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Dark green micro ATX motherboard with black heatsinks and silver accents, four DDR5 slots, three M.2 shields, rear I/O shield attached

MSI

MSI MAG B850M MORTAR WIFI AM5 Micro ATX Motherboard

SKU CH-45WR-FCD2P

AM5 micro-ATX board for Ryzen 7000, 8000 and 9000 CPUs with 12-phase 60A VRM, four DDR5 slots up to 8200 MT/s, PCIe 5.0 x16, two M.2 Gen5 slots, Wi-Fi 7, Bluetooth 5.4 and 5Gbps LAN

  • CPU socketAM5
  • ChipsetAMD B850
  • Form factorMicro ATX
  • Memory slot count4 × 288pin (DDR5)
  • Supported memorySupport DDR5 8200–5600 (OC) MT/s / 5600–4800 (JEDEC) MT/s
  • Max supported RAM256 GB
  • 60 A SPS VRM delivers stable power for Ryzen 9000 CPUs
  • DDR5 overclocking to 8200 MT/s across four slots
  • PCIe 5.0 x16 slot with Steel Armor II for high-bandwidth graphics
  • Triple M.2 connectors including two Gen5 x4 and one Gen4 x2
  • Wi-Fi 7 plus 5 Gbps LAN and Bluetooth 5.4 for fast networking

Compact AM5 Platform

The MSI MAG B850M MORTAR WIFI is a micro ATX motherboard built around the AMD B850 chipset and AM5 socket. It supports Ryzen 7000, 8000 and 9000 series processors with a 12-phase 60A SPS VRM design. Four DDR5 slots allow up to 256GB of memory at speeds up to 8200 MT/s when overclocked.

Suited for Compact Builds

This board suits builders who want a smaller chassis with modern connectivity including Wi-Fi 7, Bluetooth 5.4 and 5Gbps LAN. It provides one PCIe 5.0 x16 slot, two M.2 Gen5 slots and one M.2 Gen4 slot. Users requiring multiple full-length PCIe slots or extensive legacy I/O should consider a full-size ATX alternative.

PCIe 5.0 x16 From CPU

The primary expansion slot runs at PCIe 5.0 x16 directly from Ryzen 9000 or 7000 series CPUs, delivering 128GB/s bandwidth for current graphics cards. With Ryzen 8000 series processors the same slot operates at PCIe 4.0 x8, which may limit high-end GPU performance.

How it compares

Measured against everything we stock in Motherboards for AMD CPUs, at today’s prices. Recalculated every night.

Price $216.99
Typical for this category: the median of 1,906 items is $224.49.

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Specifications

Product
Brand nameMSI
Model nameMAG B850M MORTAR WIFI
Processor
CPU socketAM5
ChipsetAMD B850
Memory
Memory slot count4 × 288pin (DDR5)
Supported memorySupport DDR5 8200–5600 (OC) MT/s / 5600–4800 (JEDEC) MT/s
Max supported RAM256 GB
Memory channelsDual Channel
ECC supportNon-ECC
BufferingUn-buffered
Storage
SATA ports4 x SATA 6Gb/s
M.2 slotsM2_1 slot
- Supports up to PCIe 5.0 x4 (For Ryzen 9000/ 7000 Series processors)
- Supports up to PCIe 4.0 x4 (For Ryzen 8000 Series processors)
M2_2 slot
- Supports up to PCIe 5.0 x4 (For Ryzen 9000/ 7000 Series processors)
- Supports up to PCIe 4.0 x4 (For Ryzen 8700/ 8600/ 8400 Series processors)
- Supports up to PCIe 4.0 x2 (For Ryzen 8500/ 8300 Series processors)
M2_3 slot
- Supports up to PCIe 4.0 x2
Audio & video
Audio chipRealtek ALC4080
Sound channels7.1 Channels
Connectivity
Maximum network speed5 Gbit/s
Wi-Fi standardWi-Fi 802.11 be
Bluetooth support5.4
Ports & slots
PCIe 5.0 x16 slotsPCI_E1 Gen PCIe 5.0 supports up to x16 (From CPU)
PCI_E1 slot
- Supports PCIe 5.0 x16 (For Ryzen 9000/ 7000 Series processors)
- Supports PCIe 4.0 x8 (For Ryzen 8700/ 8600/ 8400 Series processors)
- Supports PCIe 4.0 x4 (For Ryzen 8500/ 8300 Series processors)
PCIe 4.0 x16 slotsPCI_E2 Gen PCIe 4.0 supports up to x4 (From Chipset)
Onboard USB headers4 x USB 2.0 ports
2 x USB 5 Gbit/s Type A ports
1 x USB 10 Gbit/s Type C ports
Power
Power connectors1 x Power Connector(ATX_PWR)
2 x Power Connector(CPU_PWR)
1 x Power Connector(PCIE_PWR 8pin)
Size & build
Form factorMicro ATX
Width and length9.6 in × 9.6 in
Compatibility
Windows 11 supportSupport for Windows 11 64-bit

Questions about this item

Will this board fit in a standard micro-ATX case and what CPU coolers clear the VRM heatsinks?

The board uses the micro-ATX form factor so it mounts in any case that accepts that size. The extended VRM heatsink and choke pads sit close to the socket; low-profile or top-flow coolers up to the case’s stated height limit will clear them, while tall tower coolers should be checked against the heatsink width before purchase.

Which Ryzen processors run the primary PCIe slot at 5.0 x16 versus 4.0 x8 and how does that affect my GPU choice?

Ryzen 7000 and 9000 series CPUs drive the top PCIe 5.0 x16 slot at full 5.0 x16 bandwidth. Ryzen 8000 series CPUs limit the same slot to 4.0 x8. Any modern graphics card works in either mode; the bandwidth difference only appears in synthetic tests with the fastest cards at 4K.

What memory kits are officially supported up to 8200 MT/s and do I need to enable EXPO manually?

The board validates DDR5 kits up to 8200 MT/s (OC) with 1 DIMM per channel, single-rank modules. JEDEC speeds run at 4800–5600 MT/s automatically. EXPO profiles must be enabled in the BIOS after installing a certified kit; the board will not apply them by default.

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