Name: MSI PRO B840M-B Micro-ATX Motherboard, AMD B840 Chipset, AM5 Socket, Ryzen 9000/8000/7000 Support, 2-Slot DDR5 128GB 8000+MHz OC, Dual PCIe 4.0 M.2, PCIe 4.0 x16, 2.5G LAN, HDMI 2.1, VGA, Front USB-C, EZ PCIe Clip II | Black
SKU: 911-7E76-002

Description

MSI PRO B840M-B — AM5 Micro-ATX Motherboard

A dependable AM5 foundation for compact productivity builds. The MSI PRO B840M-B combines AMD B840 chipset support with Ryzen 9000, 8000, and 7000 Series desktop processor compatibility, dual-channel DDR5 memory, two PCIe 4.0 M.2 SSD slots, and Realtek 2.5Gb Ethernet. Its practical micro-ATX layout, digital 7+2+1 power design, and MSI EZ DIY features make it a versatile starting point for modern desktop PCs.

Expert Features

AMD AM5 Platform: Supports AMD Ryzen 9000 / 8000 / 7000 Series desktop processors with the AMD B840 chipset.
Dual-Channel DDR5: Two DDR5 UDIMM slots support up to 128GB memory and overclocked speeds up to 8000+ MT/s, subject to CPU, memory, and BIOS compatibility.
Dual Lightning Gen4 M.2: Two PCIe 4.0 x4 M.2 slots deliver high-bandwidth NVMe SSD connectivity, alongside four SATA 6Gb/s connections.
PCIe 4.0 Expansion: Main PCIe x16-size slot supports Gen4 graphics-card connectivity, with operating lanes dependent on the installed Ryzen processor; a secondary PCIe 3.0 x1 slot is also available.
2.5G Wired Networking: Realtek 8125D 2.5Gb Ethernet provides fast, low-latency wired connectivity.
Digital 7+2+1 Power Design: A robust power architecture with a six-layer PCB and 2oz copper supports steady system operation.
Builder-Friendly EZ DIY: EZ PCIe Clip II, EZ M.2 Clip II, EZ Debug LEDs, and EZ Memory Detection LED help simplify installation and troubleshooting.
Convenient Recovery Controls: Dedicated rear Flash BIOS and Clear CMOS buttons simplify firmware maintenance and recovery.
Practical USB Connectivity: Rear USB-A 5Gbps and USB 2.0 ports, plus internal headers for front USB-A, USB-C, and USB 2.0 connections.
Flexible Case and Display Support: Compact micro-ATX form factor, HDMI 2.1 and VGA outputs (only with a CPU that has integrated graphics), RGB headers, and 7.1-channel HD audio.

Expert Specifications

Brand / Series	MSI PRO Series
Model	PRO B840M-B
Chipset	AMD B840
CPU Socket	AMD AM5
Processor Compatibility	AMD Ryzen 9000, 8000 and 7000 Series desktop processors; consult MSI CPU support list for BIOS requirements
Form Factor	Micro-ATX (mATX)
Board Dimensions	Approx. 226 × 243.84mm (per MSI product specification)
Memory Slots	2 × DDR5 UDIMM
Maximum RAM	128GB
Memory Speeds	DDR5 up to 8000+ MT/s (OC); supported speed varies with CPU and module configuration
Memory Modes	Dual-channel; AMD EXPO; non-ECC unbuffered DDR5
Main Graphics Slot	1 × PCIe 4.0 x16 physical slot (electrical lanes depend on installed processor)
Additional Expansion	1 × PCIe 3.0 x1
M.2 Storage	2 × PCIe 4.0 M.2 sockets, up to x4; second slot runs up to x2 with selected Ryzen 8500/8300 CPUs
SATA Storage	4 × SATA 6Gb/s
RAID Support	SATA RAID 0/1/10; M.2 NVMe RAID 0/1
Ethernet	Realtek 8125D 2.5Gbps LAN
Integrated Wi-Fi / Bluetooth	None on the PRO B840M-B; do not confuse with the separate PRO B840M-B WIFI6E model
Audio	Realtek ALC897, 7.1-channel HD audio
Rear HDMI	1 × HDMI 2.1, up to 4K at 60Hz with supported integrated-graphics processor
Rear VGA	1 × VGA; output requires a processor with integrated graphics
Rear USB	4 × USB-A 5Gbps; 2 × USB 2.0
Front USB Headers	1 × USB-C 5Gbps (front); headers for 2 × USB-A 5Gbps and 4 × USB 2.0 (front)
Rear Networking / Audio	1 × 2.5G RJ-45; 3 × audio jacks
Rear Control Buttons	Flash BIOS; Clear CMOS
Power Design	Direct 7+2+1 digital VRM phases
Power Connectors	24-pin ATX main power; 8-pin CPU power
PCB	6-layer PCB with 2oz thickened copper
Cooling Headers	1 × CPU fan; 2 × system fan headers
RGB Headers	3 × addressable V2 RGB headers; 1 × conventional RGB header
Diagnostics	4 × EZ Debug LEDs; 1 × EZ Memory Detection LED
EZ DIY Features	EZ PCIe Clip II; EZ M.2 Clip II; MSI Click BIOS X
Supported OS	Windows 11 64-bit
Included CPU / RAM / SSD	Not included — motherboard only