We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Green microATX motherboard with silver heatsinks, AM5 socket, four DDR5 slots, PCIe 5.0 x16 slot, dual M.2 covers

ASUS

ASUS PRIME B840M-A AMD B840 AM5 microATX motherboard

SKU CH-W4JJ-6BXY5

MicroATX board for AM5 CPUs up to 140W TDP with 256GB DDR5 6400MHz, PCIe 5.0 x16 graphics slot, dual M.2 slots, 2.5Gb LAN and USB 3.2 Gen 2 Type-C

  • CPU Socket TypeAM5
  • Supports Ryzen 9000, 8000 and 7000 series CPUs up to 140W TDP
  • Four DDR5 DIMM slots hold up to 256GB memory at 6400+ MHz OC with AMD EXPO
  • PCIe 5.0 x16 graphics slot plus dual M.2 slots at PCIe 5.0 x4 and 4.0 x4 for NVMe SSDs
  • Realtek 2.5Gb Ethernet provides low-latency wired networking for gaming and streaming
  • USB 3.2 Gen 2 Type-A and Type-C on rear I/O plus front-panel Type-C for fast peripherals

AM5 microATX board for Ryzen 7000 8000 9000

This microATX motherboard uses the AMD B840 chipset and AM5 socket. It supports Ryzen 7000 8000 and 9000 series processors with a maximum TDP of 140W. Four DDR5 DIMM slots allow up to 256GB of memory running at 6400 MHz or higher via AMD EXPO profiles. The board targets builders who want a compact platform for current and next generation Ryzen CPUs.

Check CPU cooler clearance and power phase count

Verify that your chosen AM5 cooler fits the microATX layout and can handle up to 140W TDP. Ensure your power supply provides an 8 pin EPS connector for the CPU voltage regulator. Confirm that your DDR5 modules are on the vendor qualified vendor list for EXPO stability. The board offers one PCIe 5.0 x16 slot and two M.2 slots so plan graphics and NVMe storage accordingly.

Sustained load behaviour with 140W CPUs

The voltage regulator must deliver continuous current for 140W processors during long rendering or compile sessions. Adequate case airflow over the VRM heatsinks prevents thermal throttling. The PCIe 5.0 x16 slot and PCIe 5.0 M.2 slot maintain full bandwidth under extended GPU and NVMe workloads. Realtek 2.5Gb Ethernet and USB 3.2 Gen 2 ports sustain throughput without overheating.

Highlights

  • Supports Ryzen 9000, 8000 and 7000 series CPUs up to 140W TDP
  • Four DDR5 DIMM slots hold up to 256GB memory at 6400+ MHz OC with AMD EXPO
  • PCIe 5.0 x16 graphics slot plus dual M.2 slots at PCIe 5.0 x4 and 4.0 x4 for NVMe SSDs
  • Realtek 2.5Gb Ethernet provides low-latency wired networking for gaming and streaming
  • USB 3.2 Gen 2 Type-A and Type-C on rear I/O plus front-panel Type-C for fast peripherals

Specifications

CPU Socket TypeAM5

Questions about this item

What comes in the box with the ASUS PRIME B840M-A and what must be bought separately?

The board includes the motherboard, I/O shield and driver disc; a compatible AM5 CPU cooler and DDR5 memory must be purchased separately.

Which DDR5 capacity should I choose for the four DIMM slots?

Four slots support up to 256 GB total; populate two slots first for best 6400 MHz OC stability with AMD EXPO kits.

What does the PCIe 5.0 x16 slot mean for a graphics card in this board?

The PCIe 5.0 x16 slot delivers full bandwidth for current and next-gen GPUs, while the primary M.2 runs at PCIe 5.0 x4 for fastest NVMe drives.

Also in this aisle

People compared these

Same shelf, same checkout — eight coins and a 30-minute rate lock.