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Green rectangular micro-ATX board with silver heatsinks, black PCB, rear I/O shield and M.2 covers

ASUS

ASUS PRIME B840M-A WIFI-CSM 90MB1J20-MVAAYC AMD motherboard

SKU CH-X15P-NRPS5 MPN 90MB1J20-MVAAYC

Micro-ATX AM5 board with DDR5 support to 7600 MT/s, three M.2 slots, Wi-Fi 6E and 2.5Gb Ethernet for Ryzen 7000, 8000 and 9000 series CPUs

  • CPU Socket TypeAM5
  • CPU TypeRyzen 7000 Series / Ryzen 8000 Series / Ryzen 9000 Series
  • ChipsetAMD B840
  • Number of Memory Slots4x288pin (DDR5)
  • Memory StandardUp to 7600+MT/s (OC)
  • Maximum Memory Supported192GB

Option PRIME B840M-A WIFI-CSM

Struck-through versions exist but are not stocked here.

  • Ready for Ryzen 9000, 8000 and 7000 series processors on AM5 socket
  • Four DDR5 slots support up to 192 GB at 7600 MT/s with AMD EXPO
  • Three M.2 slots at PCIe 4.0 x4 plus four SATA 6 Gb/s ports
  • Wi-Fi 6E and Realtek 2.5Gb Ethernet for fast wired and wireless links
  • CSM programme plus 6-layer PCB, alloy chokes and durable capacitors for long-term stability

ASUS PRIME B840M-A WIFI-CSM AM5 Motherboard

The ASUS PRIME B840M-A WIFI-CSM is a Micro ATX motherboard built on the AMD B840 chipset for Socket AM5 processors. It supports Ryzen 7000, 8000 and 9000 series CPUs and provides four DDR5 memory slots with a maximum capacity of 192 GB. The board includes Wi-Fi 6E, 2.5Gb LAN and rear USB 5Gbps Type-C connectivity for modern peripheral support.

Suited to compact AI-ready builds.

This board suits builders who want a compact AM5 platform with three M.2 slots, PCIe 4.0 graphics support and corporate-stable firmware for long-term deployments. The single PCIe 4.0 x16 slot and two chipset x1 slots limit multi-GPU configurations, so users planning multiple graphics cards should look at ATX chipsets with more full-length slots.

Three M.2 slots define storage flexibility

The deciding specification is the trio of M.2 slots: one CPU-attached 2280 slot running at PCIe 4.0 x4, a second CPU-attached slot accepting 2242, 2260 or 2280 drives at PCIe 4.0 x4, and a third chipset-attached 2280 slot. This layout determines how many high-speed drives can be installed directly on the motherboard.

Highlights

  • Ready for Ryzen 9000, 8000 and 7000 series processors on AM5 socket
  • Four DDR5 slots support up to 192 GB at 7600 MT/s with AMD EXPO
  • Three M.2 slots at PCIe 4.0 x4 plus four SATA 6 Gb/s ports
  • Wi-Fi 6E and Realtek 2.5Gb Ethernet for fast wired and wireless links
  • CSM programme plus 6-layer PCB, alloy chokes and durable capacitors for long-term stability

Specifications

BrandASUS
ModelPRIME B840M-A WIFI-CSM
Part Number90MB1J20-MVAAYC
CPU Socket TypeAM5
CPU TypeRyzen 7000 Series / Ryzen 8000 Series / Ryzen 9000 Series
ChipsetAMD B840
Number of Memory Slots4x288pin (DDR5)
Memory StandardUp to 7600+MT/s (OC)
Maximum Memory Supported192GB
Channel SupportedDual Channel
Memory Performance ProfileAMD EXPO
ECC SupportedYes
Buffer SupportedUn-buffered
Memory FeatureDual channel memory architecture
Supports AMD Extended Profiles for Overclocking (EXPO)
ASUS Enhanced Memory Profile (AEMP)
PCI Express 4.0 x16AMD Ryzen 9000 & 7000 Series Desktop Processors*
1 x PCIe 4.0 x16 slot (supports x16 mode)
AMD Ryzen 8000 Series Desktop Processors
1 x PCIe 4.0 x16 slot (supports x8/x4 mode)
PCI Express 3.0 x16AMD B840 Chipset
2 x PCIe 3.0 x16 slots (support x1 mode)
Serial ATA (SATA)4 x SATA 6Gb/s
M.2AMD Ryzen 9000 & 8000 & 7000 Series Desktop Processors
M.2_1 slot (Key M), type 2280 (supports PCIe 4.0 x4 mode)
M.2_2 slot (Key M), type 2242/2260/2280 (supports PCIe 4.0 x4 mode)
AMD B840 Chipset
M.2_3 slot (Key M), type 2280 (supports PCIe 3.0 x4 mode)
SATA RAIDAMD RAIDXpert2 Technology supports both PCIe RAID 0/1/5/10 and SATA RAID 0/1/5/10.
*RAID 5 Function is only supported by AMD Ryzen 9000 series CPU.
Audio ChannelsRealtek 7.1 Surround Sound High Definition Audio CODEC*
- Supports: Jack-detection, Multi-streaming, Front Panel Jack-retasking
- Supports up to 24-Bit/192 kHz playback
Audio Features
- Audio Shielding
- Premium audio capacitors
- Dedicated audio PCB layers
* A chassis with an HD audio module in the front panel is required to support 7.1 Surround Sound audio output.
Max LAN Speed2.5Gbps
Wireless LANWi-Fi 802.11 ax
BluetoothBluetooth 5.3
Back I/O Ports2 x USB 10Gbps ports (2 x Type-A)
1 x USB 5Gbps port (1 x USB Type-C)
4 x USB 2.0 ports (4 x Type-A)
2 x DisplayPort
1 x HDMI port
1 x Wi-Fi module
1 x Realtek 2.5Gb Ethernet port
3 x Audio jacks
1 x BIOS FlashBack button
Onboard USB1 x USB 5Gbps connector (supports USB Type-C)
1 x USB 5Gbps header supports 2 additional USB 5Gbps ports
2 x USB 2.0 headers support 4 additional USB 2.0 ports
Other ConnectorsFan and Cooling Related
1 x 4-pin CPU Fan header
1 x 4-pin CPU OPT Fan header
1 x 4-pin AIO Pump header
3 x 4-pin Chassis Fan headers
Miscellaneous
3 x Addressable Gen 2 headers
1 x Clear CMOS header
1 x COM Port header
1 x Front Panel Audio header (F_AUDIO)
1 x S/PDIF Out header
1 x SPI TPM header (14-1 pin)
1 x 10-1 pin Front System Panel header
Form FactorMicro ATX
Dimensions (W x L)9.6" x 9.6"
Power Pin1 x 24-pin Main Power connector
1 x 8-pin +12V CPU Power connector
BIOS Feature256 Mb Flash ROM, UEFI AMI BIOS
SoftwareASUS Exclusive Software
Armoury Crate
- Aura Creator
- Aura Sync
- Fan Xpert 2+
- Power Saving
ASUS DriverHub
ASUS GlideX
TurboV Core
ASUS CPU-Z
Norton 360 Deluxe (60 Days Free Trial)
WinRAR (40 Days Free Trial)
UEFI BIOS
ASUS EZ DIY
- ASUS CrashFree BIOS 3
- ASUS EZ Flash 3
- ASUS UEFI BIOS EZ Mode
- ASUS MyHotkey
Windows 11Windows 11, Windows 10 64-bit
FeaturesASUS 5X PROTECTION III
- DIGI+ VRM
- LANGuard
- Overvoltage protection
- SafeSlot Core+
- Stainless-steel back I/O
ASUS Q-Design
- Q-Antenna
- Q-Dashboard
- Q-DIMM
- Q-LED Core
- Q-Slot
ASUS Thermal Solution
- M.2 heatsink
- VRM heatsink design
ASUS EZ DIY
- BIOS FlashBack button
- BIOS FlashBack LED
- Pre-mounted I/O shield
Aura Sync
- Addressable Gen 2 headers
Package ContentsCables
2 x SATA 6Gb/s cables
Miscellaneous
1 x ASUS WiFi Q-Antenna
1 x M.2 rubber package
3 x Screw packages for M.2 SSD
Documentation
1 x Quick start guide
Shipping weight1.13 kg
Package size279 × 279 × 76 mm

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