Name: PRIME B840M-K
Brand: ASUS
SKU: 35757

PRIME B840M-K

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B840M-K

ASUS Prime series motherboards are expertly engineered to unleash the full potential of AMD Ryzen^™ 9000 series processors. The PRIME B840M-K 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.

8+2+1

phase digital power design

AEMP

for enhanced DDR5 performance

2.5Gb Ethernet

for faster data transfers

AI Solutions

for advanced AI capabilities

USB 5Gbps Type-C^®

for rapid data transmission

PCIe 4.0 slots

for graphics card and storage

EZ PC DIY

for easier build customization

ASUS FAN Xpert 2+

for ultimate cooling control

Aura Sync

for full RGB lighting control

Performance

AI Solutions

ASUS AI Solutions include AI Cache Boost to supercharge large language model (LLM) workflows, ASUS AI Advisor as your technical expert with expertise in PC performance.

AI Cache Boost

Supercharge your large language model (LLM) workflows with AI Cache Boost. Exclusive to ASUS AMD 800 and 600 series motherboards that use Ryzen^™ 9000 Series CPUs, this BIOS setting optimizes CPU cache and memory pathways to deliver up to 29% faster local LLM performance with high-speed memory tuning.

AI Advisor

ASUS AI Advisor allows users to explore the functionality and advanced features of ASUS motherboards in a simple and straightforward way.¹

Performance

Digital Power Design

PRIME B840M-K 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.

Vcore power

SOC power

Misc power

Angled top-down view of PRIME B840M-K motherboard.

Six-layer PCB design

Enhanced stability and overclocking.

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.

Digi+ VRM control

Real-time voltage control.

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-K 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-K offers extensive AMD Extended Profiles for Overclocking (EXPO^™) support and a wide array of UEFI settings for further performance tweaks.³

Dual M.2 slots (up to 64Gbps)

PRIME B840M-K offers two M.2 slots that support data-transfer speeds of up to 64 Gbps via PCIe 4.0, enabling quicker boot-up and app load times with OS or application drives.⁴

Graphic depicting different M.2 slots on a motherboard.

Cooling

Cooler by design

The PRIME B840M-K 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.

VRM heatsink and thermal pad

One massive VRM heatsink and essential thermal pad improve heat transfer from the MOSFETs and chokes for better cooling performance.

4-Pin PWM/DC fan

Each onboard header supports auto-detection of PWM or DC fans.

Multiple temperature sources

Except for the CPU fan header, each fan header can be set to monitor and react to up to three user-configurable thermal sensors for workload-based cooling, and all settings can be easily managed through Fan Xpert 2+ or via the UEFI.

Fan Xpert 2+ allows you to map the temperature of supported ASUS graphics cards to optimize cooling for GPU- and CPU-intensive tasks.

Passive chipset heatsink

An aluminum passive chipset heatsink ensures optimal cooling and stable performance. It is more durable and longer-lasting than heatsinks with fans, which can be vulnerable to the buildup of dust and debris.

Smart protection

A dedicated integrated circuit protects each fan header from overheating and excess current.

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

Flexibility

Empowering connections

This motherboard offers a versatile range of connectivity, including support for PCIe 4.0 slot, 2.5Gb Ethernet and an arsenal of USB ports which includes Type-C^® connections.

2.5Gb Ethernet

PCIe 4.0

PCIe 4.0 slot

USB 5Gbps

Realtek^® 2.5Gb Ethernet

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

High Speed Transferring

Numerous USB ports support high-end rigs loaded with peripherals, including four rear USB 5Gbps Type-A ports and a front USB 5Gbps Type-C^® connector for transmission speeds of up to 5Gbps.

I/O ports highlighting four rear USB 5Gbps Type-A ports and a front USB 5Gbps Type-C® connector

Customization

Personalization

The PRIME B840M-K 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 RGB Gen 2 headers

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

Image depicting PRIME B840M-K ARGB connectors.

Customization

DIY friendly

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

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.

^© 2024 Advanced Micro Devices, Inc. All rights reserved. AMD, the AMD Arrow logo, Radeon, Ryzen and combinations thereof are trademarks of Advanced Micro Devices, Inc. Other product names used in this publication are for identification purposes only and may be trademarks of their respective owners.

Availability of ASUS AI Advisor may vary by region.
AI Advisor functions may vary by platform. ↑
Memory overclocking may vary between CPU series. Please refer to the spec table for detailed information.↑
Supported memory types, data rates (speed), and number of DRAM modules vary depending on the CPU and memory configuration. For more information, please refer to the CPU/Memory Support List under the Support tab on the product information page or visit https://www.asus.com/support/download-center/.↑
Actual transmission speeds will be lower than the theoretical maximum speed.↑
Image(s) or Video(s) for reference only.↑

Product has High-Definition Multimedia Interface.

Products certified by the Federal Communications Commission and Industry Canada will be distributed in the United States and Canada. Please visit the ASUS USA and ASUS Canada websites for information about locally available products.
All specifications are subject to change without notice. Please check with your supplier for exact offers. Products may not be available in all markets.
Specifications and features vary by model, and all images are illustrative. Please refer to specification pages for full details.
PCB color and bundled software versions are subject to change without notice.
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Specifications and features vary by model, and all images are illustrative. Please refer specification pages for full details.
*Precise specifications and features vary by model. Please refer to the specification page
The product (electrical, electronic equipment, Mercury-containing button cell battery) should not be placed in municipal waste. Check local regulations for disposal of electronic products.
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Learn more about battery usage, removal, replacement, and related safety guidelines

**Product specifications and battery design may vary depending on the model. For any questions, please contact ASUS official customer service.

PRIME B840M-K

B840M-K

8+2+1