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MOTHERBOARDS

ASUS B840M MAX GAMING AX

Global manufacturer specification

CPU socket
AM5
Chipset
AMD B840 Chipset
Form factor and dimensions
micro-ATX Form Factor 9.6 inch x 9.6 inch (24.4 cm x 24.4 cm)

B840M MAX GAMING AX motherboard, identified in the ASUS Global catalogue. Specifications below retain the manufacturer’s configuration and interface conditions.

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THE ACTUAL PRODUCT
ASUS B840M MAX GAMING AX official product image
Official product image · Image source detailsProduct imagery does not establish a retailer’s bundle or condition.
Compare with ASUS B850M AYW GAMING OC WIFI7 W

Specifications checked 17 Oct 2026Manufacturer specifications, not a hands-on test.

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The useful part.

Key strengths

Published motherboard interfaces and configuration are available from the exact-model ASUS specification source.

The checks that matter.

Before you buy

Compatibility and maximum operating modes depend on the source’s stated hardware, firmware and connection requirements; manufacturer figures are not independent measurements.

Build around it.

Works with

Products in this catalogue that list the same socket or memory type as the ASUS B840M MAX GAMING AX. A shared socket or memory type is necessary but not sufficient: check the exact CPU and memory support lists, and the BIOS version, before buying.

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Every specification. With its source.

Full specifications

Exact configuration: Global manufacturer specification · B840M MAX GAMING AX

13 specifications in 9 groups. Values are manufacturer specifications unless a row says “Measured result” or “Calculated from cited specifications”.

Platform & board

3 items
CPU socket
AM5Source
Chipset
AMD B840 ChipsetSource
Form factor and dimensions
micro-ATX Form Factor 9.6 inch x 9.6 inch (24.4 cm x 24.4 cm)Source

Memory

1 item
Memory type, slots and limit
4 x DIMM slots, max. 256GB, DDR5 Supports up to 7600+MT/s (OC) with Ryzen™ 9000 & 8000 & 7000 Series Processors, ECC and Non-ECC Un-buffered DIMM* Dual channel memory architecture Supports AMD Extended Profiles for Overclocking (EXPO™) ASUS Enhanced Memory Profile (AEMP) * Supported memory types, data rate (speed), and number of DRAM modules vary depending on the CPU and memory configuration, for more information please refer to CPU/Memory Support list under the Support tab of product information site or visit https://www.asus.com/support/download-center/. Adjustments will be made based on the specifications of mass-produced memory products available on the market. * Non-ECC, un-buffered DDR5 memory supports On-Die ECC function.Source

Expansion slots

1 item
Expansion slots and restrictions
AMD Ryzen™ 9000 & 7000 Series Desktop Processors* 1 x PCIe 4.0 x16 slot (supports x16 mode) AMD Ryzen™ 8000 Series Desktop Processors 1 x PCIe 4.0 x16 slot (supports x8/x4 mode)** AMD B840 Chipset 3 x PCIe 3.0 x16 slots (support x1 mode) * Please check the PCIe bifurcation table on the support site (https://www.asus.com/support/FAQ/1037507/). ** Specifications vary by CPU types. - To ensure compatibility of the device installed, please refer to https://www.asus.com/support/download-center/ for the list of supported peripherals.Source

Storage

1 item
Storage interfaces and restrictions
Supports 3 x M.2 slots and 4 x SATA 6Gb/s ports AMD Ryzen™ 9000 & 7000 Series Desktop Processors M.2_1 slot (Key M), type 2280 (supports PCIe 4.0 x4 mode) M.2_2 slot (Key M), type 2280 (supports PCIe 4.0 x4 mode) AMD Ryzen™ 8000 Series Desktop Processors M.2_1 slot (Key M), type 2280 (supports PCIe 4.0 x4 mode) M.2_2 slot (Key M), type 2280 (supports PCIe 4.0 x4/x2 mode)* AMD B840 Chipset M.2_3 slot (Key M), type 2242/2260/2280 (supports PCIe 3.0 x2 mode 6 x SATA 6Gb/s ports * Specifications vary by CPU types. AMD RAIDXpert2 Technology Ryzen™ 9000 Series Processors: RAID 0/1/5/10 Ryzen™ 8000 Series Processors: RAID 0/1 Ryzen™ 7000 Series Processors: RAID 0/1/10Source

USB & rear connections

2 items
USB ports and headers
Rear USB (Total 7 ports) 2 x USB 10Gbps ports (2 x Type-A) 1 x USB 5Gbps port (1 x USB Type-C®) 4 x USB 2.0 ports (4 x Type-A) Front USB (Total 9 ports) 1 x USB 5Gbps connector (supports USB Type-C®) 1 x USB 5Gbps header supports 2 additional USB 5Gbps ports 3 x USB 2.0 headers support 6 additional USB 2.0 ports * USB Type-C® power delivery output: max. 5V/3ASource
Rear-panel ports
2 x USB 10Gbps ports (2 x Type-A) 1 x USB 5Gbps port (1 x USB Type-C®) 4 x USB 2.0 ports (4 x Type-A) 1 x DisplayPort 1 x Wi-Fi module 1 x Realtek 2.5Gb Ethernet port 3 x Audio jacks 1 x BIOS FlashBack™ buttonSource

Networking

1 item
Network interfaces and requirements
1 x Realtek 2.5Gb Ethernet ASUS LANGuard; Wi-Fi 6 1x1 Wi-Fi 6 (802.11ax) Supports 2.4/5GHz frequency band Bluetooth® v5.3* * The Bluetooth® version may vary, please refer to the Wi-Fi module manufacturer's website for the latest specifications.Source

Audio

1 item
Audio interfaces
Realtek 7.1 Surround Sound High Definition Audio CODEC* - Supports: Jack-detection, Multi-streaming, Front Panel Jack-retasking - Supports up to 24-Bit/192 kHz playback Audio Features - Audio Shielding - Premium audio capacitors - Dedicated audio PCB layers * A chassis with an HD audio module in the front panel is required to support 7.1 Surround Sound audio output.Source

Power, cooling & lighting

1 item
Internal headers and connectors
Fan and Cooling Related 1 x 4-pin CPU Fan header 1 x 4-pin CPU OPT Fan header 1 x 4-pin AIO Pump header 4 x 4-pin Chassis Fan header Power Related 1 x 24-pin Main Power connector 1 x 8-pin +12V CPU Power connectors Storage Related 3 x M.2 slots (Key M) 6 x SATA 6Gb/s ports USB 1 x USB 5Gbps connector (supports USB Type-C® ) 1 x USB 5Gbps header supports 2 additional USB 5Gbps ports 3 x USB 2.0 headers support 6 additional USB 2.0 ports Miscellaneous 3 x Addressable Gen 2 headers 1 x Clear CMOS header 1 x COM Port header 1 x Front Panel Audio header (F_AUDIO) 1 x S/PDIF Out header 1 x SPI TPM header (14-1 pin) 1 x 10-1 pin Front System Panel headerSource

BIOS, software & diagnostics

2 items
CPU support and BIOS requirements
AMD Socket AM5 for AMD Ryzen™ 9000 & 8000 & 7000 Series Desktop Processors* Supports up to AMD 170W CPU * Refer to https://www.asus.com/support/download-center/ for CPU support list. BIOS: 256 Mb Flash ROM, UEFI AMI BIOS

Exact CPU support and BIOS revision depend on the processor and the current ASUS CPU support list; the family statement is not a guarantee for every processor.

Source
Listed operating systems
Windows® 11, Windows® 10 64-bitSource
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