ASRock B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5
ASRock B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5, photo 2
ASRock B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5, photo 3
ASRock B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5, photo 4
ASRock B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5, photo 5
ASRock B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5, photo 6
ASRock

ASRock B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5

SKU HC-434851MPN 90-MXBR8-A0UAYZ

  • AM5
  • B850
  • Micro-ATX

Highlights

  • AMD B850 chipset, AM5 socket, supports Ryzen 9000/8000/7000
  • PCIe 5.0 x16 graphics slot and PCIe 5.0 M.2 for fastest GPU and SSD
  • Four DDR5 DIMM slots support up to 256 GB at 8000 MT/s overclocked
  • Three M.2 sockets (one PCIe 5.0, two PCIe 4.0) plus four SATA 6 Gbps ports
  • 2.5 Gbps LAN with Realtek RTL8125BG controller
  • Five 4-pin PWM fan headers, VRM and M.2 heatsinks, USB 3.1 Type-C front and rear

Key specs

Socket
AM5
Chipset
B850
Form factor
Micro-ATX
Memory
DDR5
Wi-Fi
No
Motherboard Chipset
AMD B850
All specifications
$109.99
  • ≈ 0.001426 BTC
  • ≈ 0.04803 ETH
  • ≈ 110.1 USDT

In stock Ships by Tue, Nov 10 when paid today.

  • Delivery to the United States: $39.90 DHL Express Worldwide · arrives Wed, Nov 11 – Mon, Nov 16 if paid today
  • Rate locked at checkout Up to 60 min to send BTC, 30 min for ETH and USDT
  • New, sealed and genuine Full manufacturer warranty
  • 30-day returns Unused items in original packaging
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Overview

A Micro-ATX motherboard built on the AMD B850 chipset for Ryzen 9000, 8000, and 7000 processors. It suits builders who want PCIe 5.0 graphics and storage in a compact form factor.

Board Layout and Cooling

The Micro-ATX PCB uses a black finish with VRM and M.2 heatsinks to manage thermals. A rear I/O backplate is included. Five 4-pin PWM headers provide fan and radiator control.

Memory and Expansion

Four DIMM slots accept DDR5 up to 8000 MT/s when overclocked, with a 256 GB maximum capacity. The primary PCIe 5.0 x16 slot runs at full x16 electrical, while a second slot provides PCIe 4.0 x4 connectivity.

Storage and Connectivity

Three M.2 sockets include one PCIe 5.0 x4 and two PCIe 4.0 x4 interfaces, alongside four SATA 6 Gbps ports. Rear I/O offers USB 3.1 Type-C, USB 3.1 Type-A, two USB 3.0 Type-A, four USB 2.0 Type-A, HDMI, DisplayPort, and 2.5 GbE LAN.

Features and Firmware

CPU and memory overclocking are supported with BIOS Flashback for recovery. The Realtek ALC897 codec handles audio. Internal headers include USB 3.1 Type-C, two USB 3.0, two USB 2.0, front-panel audio, and SPI TPM.

B850M Pro-A Motherboard Socket AM5 AMD B850 Micro-ATX DDR5 specifications

General
BrandASRock
Manufacturer part no.90-MXBR8-A0UAYZ
EAN4711581490390
Form Factor
Motherboard Form FactorMicro-ATX
CPU
CPU ManufacturerAMD
CPU SocketAM5
Motherboard
Motherboard ChipsetAMD B850
Memory
Max. Memory256 GB
Memory TypeDDR5
Memory Form FactorDIMM
Max. Memory Speed (OC)8000 MT/s
ECC SupportYes
Memory slots4x
Performance ProfileIntel XMP
Wi-Fi & LAN
LANYes
LAN Ports1x 2.5 Gbit/s
LAN ChipDragon RTL8125BG
Wi-Fi / BluetoothNo
Cooling
BackplateYes
M.2 HeatsinksYes
VRM HeatsinksYes
Internal Ports
CPU Power Supply1x 4-Pin + 1x 8-Pin
USB 3.0 / 3.1 / 3.2 (internal) Type C Header1
USB 3.0 / 3.1 / 3.2 (internal) Type C Possible Ports1
Internal Ports (continued)
USB 3.0 (internal) Header2
USB 3.0 (internal) Possible Ports4
USB 2.0 (internal) Header2
USB 2.0 (internal) Possible Ports4
Front Panel Audio HeaderYes
SPI TPM HeaderYes
External Ports
USB 3.1 (external) Type C1
USB 3.1 (external) Type A1
USB 3.0 (external) Type A2
USB 2.0 (external) Type A4
Display ConnectorsDisplayPort (1x), HDMI (1x)
Storage Ports
M.2 PCIe 4.0 x42
M.2 PCIe 5.0 x41
SATA 6G (internal)4
Expansion Slots
PCIe x16 slots (total)1
PCIe x4 slots (total)1
PCIe 5.0 x16 mechanical slot1
PCIe 4.0 x4 mechanical slot1
Fan Header
4 Pin Fan Connectors5
Audio
SoundchipRealtek ALC897
Back Connect
Back ConnectNo
Lighting
Lighting / RGBYes
Color
Primary ColorBlack

Specifications come from the manufacturer and can change without notice. Check the box contents and compatibility before ordering; our team answers questions within one business day.

Shipping & returns

Delivery to the United States: $39.90DHL Express Worldwide · arrives Wed, Nov 11 – Mon, Nov 16 if paid today

Ships from our warehouse in Germany: in stock, it leaves within 1–2 business days, tracked to the door.
ToBusiness daysThis item
GermanyDHL Paket1–2$5.90
Other EU countriesDHL Parcel International2–8$11.90–$15.90
UK, Switzerland and NorwayDHL Parcel International3–7$24.90
United States and CanadaDHL Express Worldwide2–5$39.90
Asia and the Middle EastDHL Express Worldwide2–5$49.90
Australia and New ZealandDHL Express Worldwide3–6$59.90
  • Discreet packaging Plain, unbranded box — no crypto or brand references outside
  • Returns 30 days for unused items in original packaging; faulty items are on us
Rates and delivery times by country

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