Asus Prime B840M-A

Name: Asus Prime B840M-A
Brand: Asus
SKU: 28311

Manufacturer: Asus

The Asus Prime B840M-A is a Micro-ATX motherboard built around the AM5 socket, making it compatible with AMD's current-generation processor lineup. It measures 244 mm × 244 mm and comes with a three-year warranty, dual BIOS support, and easy overclocking capability, along with RGB lighting and a straightforward BIOS reset mechanism for added convenience during setup.

On the memory side, the board accommodates up to 256GB of DDR5 RAM across four slots in a dual-channel configuration, with overclocked speeds reaching 7600 MHz. Expansion options include one PCIe 4.0 x16 slot and two PCIe 3.0 x16 slots, while storage connectivity is handled by three M.2 sockets and four SATA 3 connectors with full RAID 0, 1, 5, and 10 support. Rear I/O includes two USB 3.2 Gen 2 Type-A ports, four USB 2.0 ports, one USB Type-C, HDMI 2.1, two DisplayPort outputs, and a single RJ45 Ethernet port. The board also delivers 7.1-channel audio through three audio connectors.

Pros

Supports DDR5 memory with up to 256GB capacity across four slots, offering substantial headroom for memory-intensive workloads
Three M.2 sockets provide flexible options for high-speed NVMe storage without consuming SATA ports
Dual BIOS support combined with an easy BIOS reset mechanism reduces the risk of a failed update bricking the board
Overclocked RAM speeds up to 7600 MHz give enthusiasts meaningful tuning flexibility
Full RAID support across RAID 0, 1, 5, and 10 configurations adds versatility for storage redundancy and performance setups
Includes a TPM connector, making the board ready for hardware-level security module integration

Cons

No Wi-Fi or Bluetooth support means wireless connectivity requires additional hardware
Lacks USB Type-C ports on the rear I/O at higher speeds such as USB 3.2 Gen 2 or USB 4, limiting fast external device options
No PCIe 5.0 x16 slot restricts compatibility with next-generation expansion cards that require the faster interface
Only four fan headers may not be sufficient for builds with more elaborate cooling configurations
No S/PDIF Out port limits digital audio output options for users with compatible audio equipment

Who is this for?

This board is a solid fit for desktop builders targeting the AM5 platform who want a compact Micro-ATX footprint without sacrificing storage flexibility, thanks to its three M.2 sockets and four SATA 3 connectors. Users who plan to build a capable home workstation or enthusiast rig with DDR5 memory at overclocked speeds will find the four-slot configuration and 7600 MHz ceiling particularly useful. The full RAID 0, 1, 5, and 10 support also makes it a reasonable choice for users who need basic NAS-style or redundant storage within a standard desktop build.

Who is this NOT for?

This board is not well-suited for users who need wireless connectivity out of the box, as it lacks both Wi-Fi and Bluetooth, requiring a separate adapter for any wireless functionality. Builders planning to adopt next-generation PCIe 5.0 graphics or expansion cards will find the absence of a PCIe 5.0 x16 slot a limiting factor. Additionally, users who rely on high-speed USB Type-C connectivity on the rear panel — such as those working with modern external drives or USB4 devices — will find the rear I/O lacking, as no Gen 2 Type-C or faster USB-C ports are present.

General info:

CPU socket	AM5
form factor	Micro-ATX
supports Wi-Fi	✕
Has Bluetooth	✕
HDMI version	HDMI 2.1
Easy to overclock	✓
has RGB lighting	✓
Easy to reset BIOS	✓
Has dual BIOS	✓
CPU sockets	1
Has integrated graphics	✕
warranty period	3 years
height	244 mm
width	244 mm
Has integrated CPU	✕

The Asus Prime B840M-A is built on a Micro-ATX form factor measuring 244 mm × 244 mm and uses a single AM5 CPU socket, though it does not include an integrated CPU or integrated graphics. The board supports dual BIOS with an easy BIOS reset option, and overclocking is straightforward thanks to its built-in ease-of-overclock feature. RGB lighting is present, while Wi-Fi and Bluetooth are not supported. Video output is handled via HDMI 2.1, and the board comes with a three-year warranty.

Memory:

maximum memory amount	256GB
overclocked RAM speed	7600 MHz
memory slots	4
DDR memory version	5
memory channels	2
Supports ECC memory	✕

This board supports DDR5 memory across four slots in a dual-channel configuration, with a maximum capacity of 256GB. Overclocked RAM speeds can reach up to 7600 MHz, offering meaningful headroom for performance-oriented builds. ECC memory is not supported.

Ports:

USB 3.2 Gen 2 ports (USB-A)	2
USB 3.2 Gen 1 ports (USB-A)	1
USB 3.2 Gen 2 ports (USB-C)	0
USB 3.2 Gen 1 ports (USB-C)	0
USB 2.0 ports	4
USB 3.2 Gen 2x2 ports	0
USB 4 40Gbps ports	0
USB 4 20Gbps ports	0
Thunderbolt 4 ports	0
Thunderbolt 3 ports	0
has an HDMI output	✓
DisplayPort outputs	2
RJ45 ports	1
Has USB Type-C	✓
eSATA ports	0
DVI outputs	0
has a VGA connector	✕
PS/2 ports	0

The rear I/O panel provides a total of seven USB ports: two USB 3.2 Gen 2 Type-A ports, one USB 3.2 Gen 1 Type-A port, four USB 2.0 ports, and one USB Type-C connector — though no USB 3.2 Gen 2 Type-C, Gen 2x2, USB 4, Thunderbolt 3, or Thunderbolt 4 ports are present. Display output options include one HDMI and two DisplayPort outputs, with no DVI or VGA connectivity available. Network connectivity is covered by a single RJ45 port, and there are no eSATA or PS/2 ports on this board.

Connectors:

USB 3.2 Gen 1 ports (through expansion)	2
USB 2.0 ports (through expansion)	4
SATA 3 connectors	4
fan headers	4
USB 3.0 ports (through expansion)	2
M.2 sockets	3
Has TPM connector	✓
U.2 sockets	0
Has mSATA connector	✕
SATA 2 connectors	0

Internal connectivity is well-covered, with three M.2 sockets and four SATA 3 connectors for storage, while SATA 2 and U.2 sockets are absent, and there is no mSATA connector. Expansion headers include two USB 3.2 Gen 1 ports, two USB 3.0 ports, and four USB 2.0 ports — all accessible through panel expansion. The board also features four fan headers and a TPM connector for security module support.

Expansion slots:

PCIe 4.0 x16 slots	1
PCIe 5.0 x16 slots	0
PCIe 3.0 x16 slots	2
PCIe x1 slots	0
PCI slots	0
PCIe 2.0 x16 slots	0
PCIe x4 slots	0
PCIe x8 slots	0

The board offers a total of three PCIe slots: one PCIe 4.0 x16 slot and two PCIe 3.0 x16 slots, providing room for a primary graphics card alongside additional expansion cards. There are no PCIe 5.0 x16, PCIe 2.0 x16, PCIe x1, PCIe x4, PCIe x8, or legacy PCI slots present.

Audio:

audio channels	7.1
Has S/PDIF Out port	✕
audio connectors	3

The board supports 7.1-channel audio output through three analog audio connectors on the rear panel. There is no S/PDIF Out port available for digital audio output.

Storage:

Supports RAID 1	✓
Supports RAID 10 (1+0)	✓
Supports RAID 5	✓
Supports RAID 0	✓
Supports RAID 0+1	✕

The board supports four RAID configurations: RAID 0, RAID 1, RAID 5, and RAID 10 (1+0), covering a practical range of performance and redundancy setups. RAID 0+1 is not supported.

Final Verdict

The Asus Prime B840M-A is a competent Micro-ATX motherboard for the AM5 platform that delivers a well-rounded internal feature set within a compact footprint. Its DDR5 support with overclocked speeds up to 7600 MHz, three M.2 sockets, and broad RAID compatibility make it a practical choice for builders who prioritize storage flexibility and memory performance. The dual BIOS, TPM connector, and easy overclocking support add reliability and tuning convenience, though the absence of Wi-Fi, Bluetooth, and high-speed rear USB Type-C ports does narrow its appeal for users with wireless or high-bandwidth peripheral needs. Overall, it suits builders seeking a dependable AM5 foundation with meaningful expandability, as long as their connectivity requirements align with what the board provides.