Asus Prime B850M-A

Name: Asus Prime B850M-A
Brand: Asus
SKU: 4513

Manufacturer: Asus

The Asus Prime B850M-A is a Micro-ATX motherboard designed around AMD's AM5 platform, pairing the B850 chipset with a compact 244×244 mm footprint that suits space-conscious builds without sacrificing core functionality. It includes RGB lighting and ships with a three-year warranty, while dual BIOS support adds a layer of resilience for users who tinker with firmware settings.

Memory support extends to four DDR5 slots across two channels, with a maximum capacity of 256 GB and overclocked speeds reaching 8000 MHz. Expansion options include one PCIe 5.0 x16 slot and one PCIe 4.0 x16 slot, complemented by three M.2 sockets and four SATA 3 connectors. On the rear panel, connectivity covers two USB 3.2 Gen 2 Type-A ports, four USB 2.0 ports, one HDMI 2.1 output, two DisplayPort outputs, and a single RJ45 Ethernet port. The board also supports all four primary RAID configurations — 0, 1, 5, and 10 — and provides 7.1-channel audio through three audio connectors.

Pros

Supports both PCIe 5.0 x16 and PCIe 4.0 x16 slots, accommodating current and recent discrete graphics cards or add-in cards
Four DDR5 memory slots with dual-channel support and overclocked speeds up to 8000 MHz offer substantial memory bandwidth headroom
Three M.2 sockets alongside four SATA 3 connectors provide flexible storage configuration options
Dual BIOS adds resilience against failed firmware updates or corrupted BIOS settings
RAID 0, 1, 5, and 10 are all supported, giving users meaningful storage redundancy and performance options
Three-year warranty provides a solid coverage period for a motherboard

Cons

No USB Type-C ports of any kind on the rear panel, limiting connectivity for modern peripherals and devices
Wi-Fi and Bluetooth are absent, requiring a separate adapter for wireless functionality
No dedicated clear CMOS mechanism makes manual BIOS recovery less straightforward
ECC memory is not supported, ruling out use cases that require error-correcting RAM
No S/PDIF Out port limits digital audio output options for users relying on optical or coaxial connections

Who is this for?

This board is a solid fit for users building a capable AMD AM5 desktop in a compact Micro-ATX chassis, particularly those who want DDR5 memory support with room to grow up to 256 GB across four slots. The combination of PCIe 5.0 and PCIe 4.0 x16 slots, three M.2 sockets, and broad RAID support makes it well-suited to enthusiasts who prioritize storage flexibility and future-ready expansion. The overclocking-friendly design, dual BIOS, and RAM speeds up to 8000 MHz also appeal to users who like to tune their system without taking on excessive risk.

Who is this NOT for?

Users who need wireless connectivity out of the box will find this board limiting, as it lacks both Wi-Fi and Bluetooth, requiring an external adapter. It is equally unsuitable for those who depend on USB Type-C rear I/O, as no Type-C ports are present in any speed tier, which can be a practical shortcoming for modern peripherals and displays. Additionally, anyone building a workstation that requires ECC memory support or a compact small-form-factor system beyond Micro-ATX will need to look elsewhere.

General info:

CPU socket	AM5
chipset	B850
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 B850M-A is built around the AM5 socket and B850 chipset, housed in a Micro-ATX form factor measuring 244×244 mm, making it a compact single-socket board without an integrated CPU or integrated graphics. It supports overclocking and features RGB lighting, while dual BIOS provides added reliability when experimenting with firmware. The board does not include Wi-Fi or Bluetooth, and resetting the BIOS manually requires the standard process as there is no dedicated clear CMOS mechanism. Video output is handled through an HDMI 2.1 connection, and the board carries a 3-year warranty.

Memory:

maximum memory amount	256GB
overclocked RAM speed	8000 MHz
memory slots	4
DDR memory version	5
memory channels	2
Supports ECC memory	✕

This board accommodates DDR5 memory across four slots arranged in a dual-channel configuration, with a maximum supported capacity of 256 GB. Overclocked RAM speeds can reach up to 8000 MHz, giving users meaningful headroom for performance tuning. ECC memory is not supported, so the board is oriented toward consumer rather than workstation or server use cases.

Ports:

USB 3.2 Gen 2 ports (USB-A)	2
USB 3.2 Gen 1 ports (USB-A)	2
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 offers a total of eight USB ports: two USB 3.2 Gen 2 Type-A, two USB 3.2 Gen 1 Type-A, and four USB 2.0 ports. There is no USB Type-C connectivity of any kind, and higher-bandwidth options such as USB 4, USB 3.2 Gen 2x2, Thunderbolt 3, or Thunderbolt 4 are absent. Display output is covered by one HDMI port and two DisplayPort outputs, while legacy video connectors like VGA and DVI are not present. Network connectivity is handled by a single RJ45 port, and there are no eSATA or PS/2 ports.

Connectors:

USB 3.2 Gen 1 ports (through expansion)	2
USB 2.0 ports (through expansion)	4
SATA 3 connectors	4
fan headers	5
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

For internal connectivity, the board provides three M.2 sockets and four SATA 3 connectors for storage, with no SATA 2, mSATA, or U.2 options present. USB expansion headers include two USB 3.2 Gen 1 connectors, two USB 3.0 connectors, and four USB 2.0 connectors, allowing for additional front-panel or bracket-mounted ports. Cooling is supported through five fan headers, and a TPM connector is included for hardware-based security functionality.

Expansion slots:

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

The board offers two full-length PCIe slots: one PCIe 5.0 x16 and one PCIe 4.0 x16, covering the primary expansion needs for modern discrete graphics cards or high-speed add-in cards. There are no PCIe 3.0, 2.0, x8, x4, or x1 slots, and no legacy PCI slots are present, keeping the layout focused and minimal in keeping with the Micro-ATX form factor.

Audio:

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

The board supports 7.1-channel audio output, with three analog audio connectors available on the rear panel for connecting speakers or headsets. An S/PDIF Out port is not included, so digital optical or coaxial audio passthrough is not an option on this board.

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, 1, 5, and 10 — covering the most common setups for performance striping, mirroring, distributed parity, and combined redundancy. RAID 0+1 is not supported, though the available modes address the majority of consumer and prosumer storage array needs.

Final Verdict

The Asus Prime B850M-A presents a well-rounded Micro-ATX option for AMD AM5 builds, bringing together DDR5 memory support, a future-ready PCIe 5.0 slot, and three M.2 sockets with comprehensive RAID support in a compact footprint. Dual BIOS and overclocking headroom up to 8000 MHz add practical value for users who want some flexibility without unnecessary complexity. The absence of USB Type-C rear ports, built-in wireless, and ECC memory support does narrow its audience, but for a mainstream desktop builder who prioritizes storage versatility and platform longevity over wireless convenience, this board delivers a coherent and dependable feature set backed by a three-year warranty.