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Green Micro ATX board with silver heatsinks and black slots

ASUS

ASUS PRIME B550M-A WIFI II AMD motherboard

SKU CH-E5SM-JH7YN MPN PRIME B550M-A WIFI II

Micro-ATX AM4 board with PCIe 4.0, WiFi 6, dual M.2 slots, 128 GB DDR4 support and 8+1 DrMOS power stages

  • ProcessorSupports AMD Ryzen 5000 Series / 5000 G-Series / 4000 G-Seri
  • ChipsetAMD B550
  • Form factorMicro ATX
  • CPU socketAM4
  • Memory slot count4 × 288pin (DDR4)
  • Supported memoryDDR4 4866(OC) / 4800(OC) / 4600(OC) / 4466(OC) / 4400(OC) /

Model PRIME B550M-A WIFI II

  • PCIe 4.0 x16 slot for high-speed graphics cards
  • WiFi 6 (802.11ax) and 1Gb LAN for fast networking
  • Dual M.2 slots with one PCIe 4.0 x4 for quick storage
  • 8+1 DrMOS power stages deliver stable CPU power
  • Aura Sync RGB with Addressable Gen 2 header for lighting control

AM4 Socket for Ryzen 5000 Series

The ASUS Prime B550M-A WIFI II is a Micro ATX motherboard built on the AMD B550 chipset. It supports AMD Ryzen 5000 Series, 5000 G-Series, 4000 G-Series and 3000 Series processors. The board targets mainstream PC users and DIY builders who need a compact foundation with PCIe 4.0, WiFi 6 and 1Gb LAN connectivity.

CPU Cooler Clearance and M.2 Screw

Verify that your CPU cooler fits the AM4 mounting pattern and does not block the four DDR4 slots or the primary PCIe 4.0 x16 SafeSlot. Confirm your chassis has a standoff for the M.2 slot that supports PCIe 4.0 x4 NVMe drives. Check the ASUS CPU support list for your specific processor before ordering.

Fan Xpert 2 and Aura Sync RGB

The bundled Fan Xpert 2 utility lets you configure hybrid fan headers for balanced airflow across the VRM heatsink and PCH heatsink. Aura Sync software synchronises LED effects through the onboard RGB header and Addressable Gen 2 RGB header with compatible strips and components. These tools adjust cooling curves and lighting without extra hardware.

How it compares

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

Price $99.99
Cheaper than about 76% of the 1,906 comparable items (median $224.49).

New to this? Buying PC parts with Monero — what to check, what it costs to pay, and what is never asked for.

Specifications

Product
Brand nameASUS
Product linePrime
Model namePRIME B550M-A WIFI II
Part number90MB19 × 0-M0AAY0
Processor
ProcessorSupports AMD Ryzen 5000 Series / 5000 G-Series / 4000 G-Series / 3000 Series Processors
* Refer to www.asus.com for CPU support list.
CPU socketAM4
ChipsetAMD B550
Memory
Memory slot count4 × 288pin (DDR4)
Supported memoryDDR4 4866(OC) / 4800(OC) / 4600(OC) / 4466(OC) / 4400(OC) / 4333(OC) / 4266(OC) / 4200(OC) / 4133(OC) / 4000(OC) / 3866(OC) / 3733(OC) / 3600(OC) / 3466(OC) / 3400(OC) / 3333(OC) / 3200 / 3000 / 2933 / 2800 / 2666 / 2400 / 2133*
* Refer to www.asus.com for the Memory QVL (Qualified Vendors Lists), and memory frequency support depends on the CPU types.
Max supported RAM128 GB
Memory channelsDual Channel
Memory profilesIntel XMP 2.0
ECC supportECC memory (ECC mode) support varies by CPU
BufferingUn-buffered
Storage
SATA ports4 x SATA 6Gb/s
M.2 slotsAMD Ryzen 5000 Series/ 3000 Series Desktop Processors:
M.2_1 slot (Key M), type 2242/2260/2280/22110 (supports PCIe 4.0 x4 & SATA modes)
AMD Ryzen 5000 G-Series/ 4000 G-Series Desktop Processors:
M.2_1 slot (Key M), type 2242/2260/2280/22110 (supports PCIe 3.0 x4 & SATA modes)
AMD B550 Chipset:
M.2_2 slot (Key M), type 2242/2260/2280 (supports PCIe 3.0 x4 & SATA modes)
SATA and RAID support0/1/10
Graphics
Onboard video chipSupported only by CPU with integrated graphic
Audio & video
Audio chipRealtek 7.1 Surround Sound High Definition Audio CODEC
Sound channels7.1 Channels*
* A chassis with an HD audio module in the front panel is required to support 7.1 Surround Sound audio output.
Connectivity
Ethernet controllerRealtek 1Gb Ethernet
Maximum network speed1 Gbit/s
Wi-Fi standardWi-Fi 6
802.11 a/b/g/n/ac/ax
Bluetooth support5.2
Ports & slots
PCIe 4.0 x16 slots1 x PCI Express 4.0 x16*
* Actual support may vary by CPU.
PCIe 3.0 x16 slots1 x PCI Express 3.0 x16
PCIe x16 slots1 x PCI Express x16
PCIe x4 slots3 x PCI Express x4
PCIe x1 slots2 x PCIe 3.0 x1
PCI slots1 x PCI Slot
PS/2 ports1
Serial ports3
Video connectors1
HDMI ports1 x HDMI
Ethernet port1 x RJ45
USB 3.1 ports2 x USB 3.1
USB 3.0 ports10 x USB 3.0
USB 2.0 ports9 x USB 2.0
S/PDIF output1 x Optical, 1 x Coaxial
Game/midi ports1
Audio jacks6 Ports
Onboard USB headers1 x USB 3.2 Gen 1 header supports additional 2 USB 3.2 Gen 1 ports
2 x USB 2.0 headers support additional 4 USB 2.0 ports
Power
Power connectors1 × 24-pin Main Power connector
1 × 8-pin +12 V Power connector
Size & build
Form factorMicro ATX
Width and length9.6 in × 9.6 in
Shipping weight1.16 kg
Package size273 × 267 × 68 mm
Compatibility
Windows 11 supportReady
More details
PCI express 2.0 x161 x PCI Express 2.0 x16
ESATA1 x eSATA 3Gb/s
S/PDIF in1 x Optical, 1 x Coaxial
LightingRGB

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Questions about this item

Does the ASUS PRIME B550M-A WIFI II include WiFi 6 antennas and cables, or must I buy them separately?

The board ships with the WiFi 6 module installed and includes the external antennas and cables in the box, so no separate purchase is needed for wireless connectivity.

Which DDR4 speed should I choose for this motherboard — 3200 MHz or one of the higher OC ratings such as 4800 MHz?

The board runs DDR4 at 2133 MHz by default; speeds up to 4866 MHz are overclocked profiles that require XMP 2.0 kits and manual tuning in the BIOS.

What does the PCIe 4.0 x16 SafeSlot mean for a graphics card installed in the primary slot?

The top PCIe 4.0 x16 slot delivers full PCIe 4.0 bandwidth to a compatible Ryzen 5000 series CPU and uses a reinforced SafeSlot design for heavier cards.

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