ASUS Prime B840M-A WIFI-CSM M-ATX Motherboard

The ASUS Prime B840M-A WiFi-CSM is a Micro-ATX motherboard built on the AMD B840 chipset and designed around the AM5 socket, making it compatible with AMD Ryzen 9000, Ryzen 8000, and Ryzen 7000 series desktop processors. It is an excellent choice for compact builds that demand modern connectivity and strong memory performance without stepping up to a full-ATX form factor. Memory performance sits at the core of the PRIME B840M-A WiFi-CSM. The board supports DDR5 memory in dual-channel configuration, with speeds reaching up to 7600 MHz and beyond when using supported profiles. ASUS Enhanced Memory Profile (AEMP) automatically optimises entry-level DDR5 kits that lack native EXPO support, while full AMD EXPO compatibility is available for enthusiast-grade modules that need higher transfer rates out of the box. The board accommodates up to 256 GB of non-ECC unbuffered DDR5, with die ECC function supported by compatible memory. Storage options are generous for an mATX design. Three M.2 Key-M slots are on board: two deliver up to 64 Gbps via PCIe 4.0, and one operates on PCIe 3.0. Four SATA 6 Gb/s ports extend storage capacity further for HDDs or older SSDs. Expansion is handled by one PCIe 4.0 x16 slot — running at full x16 bandwidth with Ryzen 9000 or 7000 series CPUs — and two additional PCIe 3.0 x16 slots that operate at x1 mode from the B840 chipset. Display output on the rear panel includes two DisplayPort and one HDMI port for integrated graphics use. Wireless connectivity is covered by WiFi 6E and Bluetooth 5.3. Wired networking is provided by a Realtek 2.5 Gb Ethernet port. The rear I/O panel also carries two USB 10 Gbps Type-A ports, one USB 5 Gbps Type-C port, four USB 2.0 Type-A ports, three audio jacks, and a BIOS FlashBack button for firmware updates without a CPU installed. Internal headers are equally comprehensive, with three Addressable Gen 2 ARGB headers, multiple fan and pump headers, an S/PDIF Out header, a COM port header, and an SPI TPM header for security-conscious builds. The board ships with a three-year warranty. Verifiable Specifications: - Socket: AM5 - Chipset: AMD B840 - Compatible CPUs: AMD Ryzen 9000, 8000, and 7000 series desktop processors - Form Factor: Micro-ATX - Memory Type: DDR5 (non-ECC, unbuffered), Dual Channel - Max Memory: 256 GB - Memory Speed: Up to 7600+ MHz (EXPO / AEMP supported) - M.2 Slots: 3x Key-M (2x PCIe 4.0 up to 64 Gbps, 1x PCIe 3.0) - SATA Ports: 4x SATA 6 Gb/s - PCIe Slots: 1x PCIe 4.0 x16, 2x PCIe 3.0 x16 (x1 mode) - Wireless: WiFi 6E, Bluetooth 5.3 - Ethernet: Realtek 2.5 GbE - Rear USB: 2x USB 10 Gbps Type-A, 1x USB 5 Gbps Type-C, 4x USB 2.0 Type-A - Video Output: 2x DisplayPort, 1x HDMI - ARGB Headers: 3x Addressable Gen 2 - Warranty: 3 Years