ASUS Prime B850 Plus Wifi CSM AMD Motherboard

The ASUS Prime B850-Plus WiFi CSM is a full-size ATX motherboard built on the AMD B850 chipset, designed specifically for the AMD Socket AM5 platform. It is compatible with AMD Ryzen 9000, 8000, and 7000 series desktop processors, making it a versatile foundation for new and next-generation AMD builds alike. At the heart of its power delivery sits an 8+2+1 phase digital VRM with discrete MOSFETs, governed by ASUS's Digi+ VRM controller for real-time voltage adjustment and automatic switching between frequency and power-efficiency modes. The six-layer PCB aids heat dissipation around the voltage regulators, providing additional headroom for CPU stability under sustained workloads. Memory support is handled by four DDR5 DIMM slots capable of holding up to 256 GB in dual-channel configuration, with transfer speeds reaching up to 8000+ MT/s under overclocking conditions. The board supports both AMD EXPO and ASUS AEMP profiles to simplify memory optimisation, and accepts ECC and non-ECC unbuffered modules. Storage is served by three Key-M M.2 slots — the primary slot runs at PCIe 5.0 x4 (up to 128 Gbps) with Ryzen 9000/7000 processors, the second slot at PCIe 4.0 x4, and the third chipset-fed slot at PCIe 4.0 x2 — alongside four SATA 6 Gb/s ports. The primary PCIe x16 slot operates at full PCIe 5.0 x16 bandwidth with Ryzen 9000 and 7000 series CPUs. Connectivity includes built-in 2×2 Wi-Fi 6E (802.11ax) covering the 2.4 GHz, 5 GHz, and 6 GHz bands with Bluetooth 5.3, plus a Realtek 2.5 Gb Ethernet port protected by ASUS LANGuard. The rear I/O panel offers eight USB ports — four at 10 Gbps (three Type-A plus one Type-C), two at 5 Gbps, and two USB 2.0 — along with DisplayPort 1.4 (up to 8K@30 Hz) and HDMI 2.1 (up to 4K@60 Hz) for integrated-graphics output. Builder-friendly features include BIOS FlashBack for CPU-less firmware updates, Q-LED Core diagnostic LEDs, pre-mounted I/O shield, Q-Antenna snap-fit WiFi antenna mount, Q-DIMM single-latch memory slots, and SafeSlot-reinforced PCIe x16 slots. Three addressable RGB Gen 2 headers and Aura Sync software enable per-zone lighting customisation. The board ships with ASUS Fan Xpert 2+ for intelligent fan and pump control across six headers (one CPU fan, one CPU OPT, one AIO pump, four chassis), and ASUS 5X Protection III covering overvoltage protection, LANGuard, SafeSlot, stainless-steel I/O, and Digi+ VRM. Verified Specifications: - Chipset: AMD B850 - Socket: AM5 (Ryzen 9000 / 8000 / 7000 series) - Form Factor: ATX — 305 mm × 244 mm (12 in × 9.6 in) - Memory: 4× DDR5 DIMM, max 256 GB, up to 8000+ MT/s (OC), dual-channel, EXPO + AEMP - Primary M.2: PCIe 5.0 x4 (Ryzen 9000/7000); PCIe 4.0 x4 (Ryzen 8000) - PCIe x16 slot: PCIe 5.0 x16 (Ryzen 9000/7000); PCIe 4.0 x8/x4 (Ryzen 8000) - SATA: 4× SATA 6 Gb/s - LAN: Realtek 2.5 Gb Ethernet - Wireless: Wi-Fi 6E 2×2 (802.11ax), 2.4/5/6 GHz; Bluetooth 5.3 - Rear USB: 4× USB 10 Gbps (3× Type-A + 1× Type-C), 2× USB 5 Gbps, 2× USB 2.0 - Display: 1× DisplayPort 1.4 (8K@30 Hz), 1× HDMI 2.1 (4K@60 Hz) - Audio: Realtek 7.1 HD Audio, up to 24-bit/192 kHz - BIOS: 256 Mb Flash ROM, UEFI AMI BIOS with FlashBack