The ASUS Prime B840M‑A (also available in Wi‑Fi and CSM editions) is built around the AMD B840 chipset, featuring the AM5 socket to support Ryzen 7000 / 8000 / 9000‑series CPUs:

• Memory

  • 4 × DDR5 DIMM slots, dual‑channel support, up to 192–256 GB (depending on BIOS/variant)

  • Supports AMD EXPO OC and AEMP auto‑profiles up to ~7600 MT/s 

• CPU & PCIe Support

  • One PCIe 4.0 ×16 slot for graphics (speed varies by CPU)

  • Two additional PCIe 3.0 x16 slots wired at ×1 

• Storage

  • Three M.2 slots: two with PCIe 4.0 ×4 (M.2_1, M.2_2) and one PCIe 3.0 ×4 (M.2_3); plus 4 × SATA 6 Gb/s ports

  • RAID support (levels vary by CPU series) 

• Networking & Connectivity

  • Realtek 2.5 Gb Ethernet with ASUS LANGuard

  • On Wi‑Fi variants: integrated Wi‑Fi 6E (2×2) and Bluetooth 5.3 

• Rear I/O Ports

  • 2 × USB 10 Gbps Type‑A, 1 × USB 5 Gbps Type‑C, 4 × USB 2.0

  • Video: 2 × DisplayPort (up to 8K @30 Hz), 1 × HDMI 2.1 (4K @60 Hz)

  • BIOS FlashBack button + LED indicator

  • Gigabit audio jacks and PS/2 support 

• Power & Cooling

  • Robust 8+2+1 digital VRM power delivery

  • Includes VRM heatsinks, M.2 heatsink, multiple fan headers (CPU, OPT, AIO pump, chassis) with Fan Xpert 2+ support

  • ASUS 5X Protection III, SafeSlot Core+, Q‑LED, pre‑mounted I/O shield, Q‑Design ease‑of‑build features 

• Software & BIOS

  • UEFI BIOS with EZ FlashBack, CrashFree BIOS 3, MyHotkey

  • Armoury Crate, Aura Sync, Fan Xpert 2+, TurboV Core, AI Advisor/Bios tweaks