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Micro ATX motherboard in matte black with silver heatsinks, AM5 socket, four DDR5 slots, PCIe 5.0 x16 slot, HDMI and DisplayPort

ASRock

ASRock B850M Pro RS AMD motherboard

SKU CH-9BKZ-BEQ6A MPN B850M Pro RS

Micro-ATX AM5 board with one PCIe 5.0 x16 slot, one Gen5 M.2 and two Gen4 M.2 slots, plus 4 DDR5 DIMMs up to 256 GB

  • ProcessorRyzen 7000 Series / Ryzen 8000 Series / Ryzen 9000 Series
  • ChipsetAMD B850
  • Form factorMicro ATX
  • CPU socketAM5
  • Memory slot count4 × 288pin (DDR5)
  • Supported memoryUp to 8000+(OC)

Model B850M Pro RS

Show 4 more
  • Supports Ryzen 9000, 8000 and 7000 series processors via AM5 socket
  • 8+2+1 phase Dr.MOS power design delivers stable CPU current
  • Four DDR5 slots accept up to 256 GB at 8000+ OC
  • One PCIe 5.0 x16 slot plus one PCIe 4.0 x4 slot
  • One Blazing M.2 Gen5x4 128 Gb/s plus two Hyper M.2 Gen4x4 64 Gb/s

Socket AM5 micro-ATX board

The ASRock B850M Pro RS is a micro-ATX motherboard built on the AMD B850 chipset for Socket AM5 processors. It accepts Ryzen 7000, 8000 and 9000 series CPUs and provides four DDR5 DIMM slots with dual-channel support up to 256 GB. An 8+2+1 phase Dr.MOS power design and a 6-layer PCB deliver stable current for daily workloads and moderate overclocking.

Builders wanting Gen5 graphics and fast storage

This board suits builders who need a single PCIe 5.0 x16 slot for a modern graphics card and a CPU-linked Blazing M.2 socket running at Gen5 x4 speeds. Two additional chipset M.2 sockets operate at Gen4 x4. Users requiring multiple PCIe 5.0 x16 slots or more than three M.2 connectors should look at larger ATX models.

One PCIe 5.0 x16 slot runs at x16 with Ryzen 9000

The primary PCIe 5.0 x16 slot operates at Gen5 x16 with Ryzen 9000 and 7000 series processors, dropping to Gen4 x8 with Ryzen 8000 Phoenix 1 and Gen4 x4 with Phoenix 2. This lane allocation decides whether a high-end GPU receives full bandwidth.

How it compares

Measured against everything we stock in Motherboards for AMD CPUs, at today’s prices. Recalculated every night.

Price $110.99
Cheaper than about 73% of the 1,906 comparable items (median $224.49).

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Specifications

Product
Brand nameASRock
Model nameB850M Pro RS
Processor
ProcessorRyzen 7000 Series / Ryzen 8000 Series / Ryzen 9000 Series
CPU socketAM5
ChipsetAMD B850
Memory
Memory slot count4 × 288pin (DDR5)
Supported memoryUp to 8000+(OC)
Max supported RAM256 GB
Memory channelsDual Channel
Memory profilesAMD EXPO / Intel XMP 3.0
ECC supportYes
BufferingUn-buffered
Storage
SATA ports4 x SATA 6Gb/s
Audio & video
Audio chipRealtek ALC897
Sound channels7.1 Channels
Connectivity
Ethernet controllerDragon RTL8125BG
Maximum network speed2.5 Gbit/s
Ports & slots
PCIe 4.0 x16 slots1 x PCIe 4.0 x4 Slot (PCIE2), supports x4 mode*
Rear panel ports2 x Antenna Mounting Points
1 x HDMI Port
1 x DisplayPort 1.4
1 x USB 3.2 Gen2 Type-A Port (10 Gb/s)
1 x USB 3.2 Gen2 Type-C Port
2 x USB 3.2 Gen1 Ports
4 x USB 2.0 Ports
1 x RJ-45 LAN Port
1 x BIOS Flashback Button
HD Audio Jacks: Line in / Front Speaker / Microphone
Onboard USB headers2 x USB 2.0 Headers (Support 4 USB 2.0 ports)
2 x USB 3.2 Gen1 Headers (Support 4 USB 3.2 Gen1 ports)
1 x Front Panel Type C USB 3.2 Gen1 Header
Power
Power connectors1 × 24 pin ATX Power Connector
1 × 8 pin 12 V Power Connector (Hi-Density Power Connector)
1 × 4 pin 12 V Power Connector (Hi-Density Power Connector)
Size & build
Form factorMicro ATX
Width and length9.6 in × 9.6 in
Shipping weight1.36 kg
Package size292 × 254 × 64 mm
Compatibility
Windows 11 supportWindows OS 10 64-bit / 11 64-bit
In the box
In the box2 x SATA Data Cables
1 x Screw for M.2 Socket
More details
BIOS256Mb AMI UEFI Legal BIOS with GUI support

Other versions of this model

5 more in the same range

Questions about this item

Will this board fit in a standard micro-ATX case and still leave room for a dual-slot graphics card?

Yes, the micro-ATX form factor fits any case that accepts that size, and the single PCIe 5.0 x16 slot is positioned so a dual-slot card clears the board edge and the front-panel headers.

Which Ryzen processors run the top PCIe slot at full Gen 5 x16 speed?

Ryzen 7000 and 9000 series CPUs drive the primary slot at Gen 5 x16; Ryzen 8000 series processors limit it to Gen 4 x8 or Gen 4 x4 depending on the specific silicon.

Can I populate all four DIMM slots with 64 GB modules to reach the 256 GB maximum?

Yes, the four 288-pin DDR5 slots support up to 256 GB total when using 64 GB unbuffered DIMMs, running in dual-channel mode with AMD EXPO or Intel XMP 3.0 profiles.

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