ASUS PRIME B840M-R AMD B840 mATX Motherboard DDR5 AM5
ASUS
ASUS PRIME B840M-R AMD B840 mATX Motherboard DDR5 AM5
The ASUS PRIME B840M-R is a micro-ATX motherboard built for AMD Ryzen 9000, 8000 and 7000 series processors. It pairs DDR5 support with PCIe 4.0 connectivity and power-delivery tuning features designed for both overclocking enthusiasts and builders wanting a capable, feature-rich platform without the size of a full-size board.
Why this product
DDR5 overclocking with EXPO support
This board supports up to 7200+ MT/s with Ryzen 9000 and 7000 series CPUs, plus extensive EXPO profiles and AEMP for fine-tuned memory performance.
Dual M.2 slots with fast PCIe 4.0
The primary M.2 slot runs at PCIe 4.0 for 64 Gbps transfer speeds, enabling quick boot and load times; a secondary PCIe 3.0 slot adds storage flexibility.
6+2+1 phase power design
Discrete MOSFETs and a Digi+ VRM deliver stable, efficient power to the CPU with real-time voltage control and auto frequency switching.
Extensive USB and connectivity
Four USB 5Gbps rear ports, front USB Type-C header, Ethernet, DisplayPort and HDMI provide ample I/O for peripherals and displays.
Thermal management built in
Onboard chipset heatsink, hybrid fan headers with auto-detection for PWM or DC fans, and 2oz copper PCB design help keep temperatures stable under load.
- ChipsetAMD B840
- SocketAMD Socket AM5
- MemoryDDR5, up to 128GB (2 DIMM)
- Storage2 x M.2 (PCIe 4.0 + PCIe 3.0), 4 x SATA
- Form FactorMicro-ATX
- Power Phases6+2+1 phase with MOSFETs
- Ethernet1 x 1Gb with LANGuard
- SKUASU-2752
- EAN4711636560702
- Supports AMD Ryzen 9000, 8000 and 7000 series processors in Socket AM5, up to 120W TDP.
- Accepts DDR5 memory up to 128GB across two DIMM slots with full EXPO and AEMP support.
- Micro-ATX form factor fits standard mid-tower cases; dimensions 23.6 cm × 22.9 cm.
- Integrated graphics output via DisplayPort 1.4 (8K@30Hz) and HDMI 2.1 (4K@60Hz) on processors with iGPU.
- PCIe x16 slot runs at x16 with Ryzen 9000 and 7000, but x8/x4 with Ryzen 8000 series.
Best for
- Budget-conscious builders moving to Ryzen 9000 who want DDR5 and overclocking room without paying for larger boards.
- Compact builds that prioritise performance and feature density in a micro-ATX footprint.
- Overclockers exploring DDR5 performance via EXPO and AEFI tuning with stable power delivery.
- Users planning AI-ready systems with multiple storage drives and USB peripherals.
Trade-offs
- High-end workstations requiring 10Gb Ethernet or more than 2 M.2 slots.
- Builders needing full-size boards for extensive expansion or maximum RAM slot count.
- Legacy CPU users — this board requires Socket AM5 Ryzen 9000, 8000 or 7000 series only.
ASUS Prime series motherboards are expertly engineered to unleash the full potential of AMD Ryzen™ 9000 series processors. The PRIME B840M-R motherboard provides users and PC DIY builders with a range of performance optimizations via intuitive software and firmware features. It's designed to be Advanced AI PC-ready, offering the power and connectivity needed for demanding AI applications.
PRIME B840M-R features 6+2+1 phase power design with discrete MOSFETs, ensuring efficient and stable power delivery for AMD processors plus steady performance for day-to-day use. 2oz copper PCB design can draw heat away from critical components to keep the optimal operating temperatures. The Digi+ voltage-regulator module (VRM) delivers real-time control over voltage droop, automatically switching frequency and power-efficiency settings.
For those looking to surpass stock DDR5 speeds, the PRIME B840M-R offers extensive AMD Extended Profiles for Overclocking (EXPO™) support and a wide array of UEFI settings for further performance tweaks.
PRIME B840M-R offers a total of two M.2 slots, including one that supports data-transfer speeds of up to 64Gbps via PCIe 4.0, and one that supports PCIe 3.0. This enables quicker boot-up and app load times with OS or application drives.
The PRIME B840M-R motherboard is engineered with onboard chipset heatsink and an array of hybrid fan headers to help ensure your rig stays cool and stable under intense workloads. Each onboard header supports auto-detection of PWM or DC fans.
Numerous USB ports support high-end rigs loaded with peripherals, including four rear USB 5Gbps Type-A ports and a front USB 5Gbps Type-C® connector for transmission speeds of up to 5Gbps.
General
| Brand | ASUS |
|---|---|
| Model | PRIME B840M-R |
| Form Factor | Micro-ATX (23.6 cm × 22.9 cm) |
Processor Support
| Socket | AMD Socket AM5 |
|---|---|
| Compatible CPUs | AMD Ryzen 9000, 8000 and 7000 series |
| CPU Power Limit | Up to 120W |
Memory & Storage
| Memory Slots | 2 x DIMM (DDR5) |
|---|---|
| Max Memory | 128GB |
| Memory Speeds (Ryzen 9000/7000) | Up to 7200+ MT/s (OC) with EXPO |
| Memory Speeds (Ryzen 8000) | Up to 7600+ MT/s (OC) with EXPO |
| M.2 Slot 1 | PCIe 4.0 x4 (up to 64 Gbps) — type 2280 |
| M.2 Slot 2 | PCIe 3.0 x4 — type 2242/2260/2280 |
| SATA Ports | 4 x SATA 6Gb/s |
Connectivity & I/O
| Rear USB Ports | 4 x USB 5Gbps (Type-A), 2 x USB 2.0 (Type-A) |
|---|---|
| Front USB Headers | 1 x USB 5Gbps Type-C, 1 x USB 5Gbps header (2 ports), 2 x USB 2.0 headers (4 ports) |
| Video Output | 1 x DisplayPort 1.4 (8K@30Hz), 1 x HDMI 2.1 (4K@60Hz) |
| Ethernet | 1 x 1Gb Realtek with LANGuard |
| Audio | 3 x audio jacks |
| Legacy I/O | 1 x PS/2 keyboard/mouse combo |
Expansion & Power
| PCIe Slots | 1 x PCIe 4.0 x16 (x16 on 9000/7000, x8/x4 on 8000), 1 x PCIe 3.0 x1 |
|---|---|
| Power Design | 6+2+1 phase with discrete MOSFETs, Digi+ VRM |
| Main Power | 1 x 24-pin connector, 1 x 8-pin +12V CPU |
| Fan Headers | 1 x 4-pin CPU, 2 x 4-pin Chassis (hybrid, auto-detect PWM/DC) |
| RGB Headers | Addressable RGB Gen 2 headers with Aura Sync |
Protection & Features
| ASUS 5X Protection | Digi+ VRM, LANGuard, Overvoltage protection, SafeSlot Core+, Stainless-steel back I/O |
|---|---|
| ASUS Q-Design | Q-Dashboard, Q-DIMM, Q-LED (CPU/DRAM/VGA/Boot Device), Q-Slot |
| Thermal Design | Onboard chipset heatsink, 2oz copper PCB |
| RAID Support | RAID 0/1/5/10 via AMD RAIDXpert2 |
| Overclocking | AMD EXPO, AEMP, extensive UEFI tuning |
Shipping
All our products are shipped from the United Kingdom within 24 to 48 hours of purchase. See our Shipping and Returns page for full details.
Returns
- Tech Syndicate offers a full money-back guarantee on all purchases made in our store. If you are not satisfied with your purchase, we will provide a full refund, no questions asked.
- Refunds are available within 45 days of delivery.
- After the 45-day period you are no longer eligible for a refund, so we encourage you to try the product within the first few weeks to make sure it fits your needs.