Motherboard ASUS PRIME B840M-A-CSM AMD B840 Socket AM5 micro ATX

ASUS Prime series motherboards are expertly engineered to unleash the full potential of AMD Ryzen™ 9000 series processors. The PRIME B840M-A-CSM motherboard provides users and PC DIY builders with a range of performance optimizations via intuitive software and firmware features. It’s designed to be Advanced AI PC-ready, offering the power and connectivity needed for demanding AI applications.

ASUS Corporate Stable Model
ASUS Corporate Stable Model (CSM) is a commercial program designed to provide stable and reliable motherboards. Offering up to 36-month product lifecycle support and 6-month end-of-life notice to allow sufficient lead times for your organization to get ready for product transitions. Each purchase of an ASUS CSM motherboard comes with ASUS Control Center Express - server-grade IT management software.

ASUS Control Center Express
ASUS Control Center Express is an integrated IT monitoring and management software designed to deploy faster, simplify IT operations and improve productivity with comprehensive control and user-friendly functions. ASUS Control Center Express is compatible with over 100 ASUS motherboards to provide a high-quality, TCO-optimized solution for your business needs.

Optimize IT endpoint management
Designed to assist IT staff in monitoring and controlling devices within their corporate networks, and facilitate inventory checking in multiple locations remotely.

Automate IT maintenance
Allows IT staff to schedule automatic updates of the latest BIOS, software and utilities to specific or all devices at off-peak times, enhancing system stability and IT operational flexibility.

Securely manage all of endpoints
Securely manage endpoint configuration, portable storage access and PC software applications by enabling them to create grouping rules on individual devices.

Performance
AI Solutions
ASUS AI Solutions include AI Advisor as your technical expert with expertise in PC performance.

AI Advisor
ASUS AI Advisor allows users to explore the functionality and advanced features of ASUS motherboards in a simple and straightforward way.7

Performance
Digital Power Design
PRIME B840M-A-CSM features an 8+2+1 phase power design with discrete MOSFETs, ensuring efficient and stable power delivery for AMD processors plus steady performance for day-to-day use.5

The multi-layered printed circuit board design quickly dissipates heat around the voltage regulators to improve overall system stability and provide the CPU with more overclocking headroom.

The Power Saving function contains several settings to easily optimize power consumption and maximize energy savings. You can enable a CPU power limit, darken Aura lighting and set the fan profile to a Power Saving mode. You can also toggle the Power Saver plan that is built into Microsoft Windows.

The Digi+ voltage-regulator module (VRM) delivers real-time control over voltage droop, automatically switching frequency and power-efficiency settings.

Enhanced Memory & Storage Performance
Enhanced DDR5 performance
Comprehensive memory tuning options are the cornerstone of PRIME motherboards. The PRIME B840M-A-CSM maximizes the potential of your DDR5 modules, from entry-level to extreme-speed kits.2
For entry-level modules without EXPO™ support, ASUS Enhanced Memory Profile (AEMP) automatically detects memory chips and provides optimized profiles for enhanced performance.
For those looking to surpass stock DDR5 speeds, the PRIME B840M-A-CSM offers extensive AMD Extended Profiles for Overclocking (EXPO™) support and a wide array of UEFI settings for further performance tweaks.3

Three M.2 slots (up to 64 Gbps)
PRIME B840M-A-CSM offers a total of three M.2 slots, including two that support data-transfer speeds of up to 64 Gbps via PCIe 4.0, and one that supports PCIe 3.0. This enables quicker boot-up and app load times with OS or application drives.4

Cooling
Cooler by design
The PRIME B840M-A-CSM motherboard is engineered with multiple onboard heatsinks and an array of hybrid fan headers to help ensure your rig stays cool and stable under intense workloads.

Smart Cooling precision

ASUS Fan Xpert 2+
ASUS Fan Xpert 2+ software provides comprehensive control over fans. An Auto-Tuning mode intelligently configures all parameters with a single click. There’s also an Extreme Quiet mode that reduces chassis fan speeds to below the default minimum to keep your system whisper-quiet when performing light tasks. Fans can also be controlled via the UEFI BIOS.5

Cooler compatibility
ASUS AIO coolers offer robust performance, high overclocking potential, bold aesthetics and customizable functionality for new motherboards, empowering you to build your dream gaming rig.5

Flexibility
Empowering connections
This motherboard offers a versatile range of connectivity, including support for PCIe 4.0 slot and an arsenal of USB ports which includes Type-C® connections.

Realtek 2.5 Gb Ethernet
Realtek 2.5 Gb Ethernet reduces CPU overhead and offers exceptionally high TCP and UDP throughput for faster, smoother data transfers.

Front USB 5Gbps Type-C®
This motherboard features a USB 5Gbps Type-C® front panel connector for speedy data transfers of up to 5Gbps.5

Customization
Personalization
The PRIME B840M-A-CSM enhances the user experience across the board, from simplifying BIOS setting adjustments to offering customizable RGB lighting controls for a uniquely personal system aesthetic.

UEFI BIOS
The UEFI interface delivers easy-to-use configuration options for PC beginners, and advanced features for veterans.

ASUS DriverHub
Simplify driver management with automatic detection, one-click installation and update for smooth, efficient system performance.

Armoury Crate
Customize Aura Sync RGB and control ASUS devices. Includes product registration and updates.

Aura Sync
Complete RGB lighting control for enthusiast systems, ensuring seamless synchronization with compatible hardware.

Addressable Gen 2 RGB headers
Three addressable Gen 2 headers detect LED counts on compatible RGB devices, automatically adjusting lighting effects accordingly.

Customization
DIY friendly
The PRIME B840M-A-CSM motherboard features EZ PC DIY innovations that simplify and speed up the PC building process, making DIY easy and convenient.

Pre-mounted I/O shield
Our pre-installed I/O shield safeguards ports, simplifies the build process, increases functionality and enhances aesthetics for PC DIY enthusiasts.

BIOS FlashBack™
BIOS FlashBack™ simplifies BIOS updates. Just load the BIOS file onto a FAT32 USB stick, insert it into the BIOS FlashBack™ port, and press a button — no CPU or memory needed.

SafeSlot Core+
SafeSlot Core+ is a one-piece stainless-steel brace that shields the slot to protect it from damage. The metal cover is tightly secured to the slot with hooks, and the entire assembly is firmly anchored to the PCB with strengthened solder points to provide a secure foundation for heavyweight graphics cards.

Q-LED Core
The Q-LED Core display produces color-coded lights during the Power-On Self-Test (POST) that can help you troubleshoot potential issues.

Build for the most advanced pc for gaming and creating
When only the fastest will do, ASUS motherboards deliver. With faster dual-channel DDR5 memory support, AMD EXPO™ technology and PCIe® 4.0 support for both graphics and NVMe, you can play the most demanding games and deliver your biggest projects with the revolutionary performance of an ASUS motherboard and AMD Ryzen™ 9000, 8000, and 7000 Series processors.

How to use

Install the motherboard into a compatible micro‑ATX case, mount the CPU and DDR5 memory modules according to the motherboard manual, and connect storage devices to the appropriate M.2 slots or SATA ports. Attach power connectors from a suitable PSU to the 24-pin ATX and CPU power headers, connect front-panel USB Type-C if available, and install the GPU into the reinforced PCIe slot if required. Use the UEFI BIOS for initial configuration, enable or tune memory profiles (AEMP or EXPO) as needed, configure fan curves with ASUS Fan Xpert 2+ or via UEFI, and update drivers using ASUS DriverHub. For IT deployments, enroll devices in ASUS Control Center Express to enable remote monitoring, automated BIOS and software updates, and endpoint grouping rules.

Recommendations

For stable enterprise deployments, register the board with the ASUS CSM program and use ASUS Control Center Express to schedule off‑peak BIOS and utility updates. When building high-performance systems, pair the PRIME B840M-A-CSM with quality DDR5 kits (preferably with EXPO profiles for overclocking), an efficient CPU cooler compatible with provided headers, and a PSU that supports the board’s power requirements.