ASUS PRIME B850M-A-CSM micro ATX motherboard
£151.14 inc VAT
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About This Item
- Supports AMD Ryzen 7000/8000/9000 Series processors on Socket AM5
- Three M.2 slots with PCIe 5.0 and PCIe 4.0 support for up to 128 Gbps speeds
- Dual-channel DDR5 memory support up to 256 GB at 8000 MHz with ECC compatibility
- micro ATX form factor with 7.1 channel audio and Realtek 2.5 Gb Ethernet
- Four SATA III connectors and RAID 0/1/5/10 support for versatile storage options
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ASUS PRIME B850M-A-CSM | Micro ATX Powerhouse for AMD Ryzen
The ASUS PRIME B850M-A-CSM AMD B850 Socket AM5 micro ATX motherboard is engineered for users seeking a stable, high-performance foundation for AMD Ryzen 7000, 8000, and 9000 series processors. Built with the Corporate Stable Model program, it delivers long-term reliability and advanced features for both business and enthusiast builds.
Specification Overview
| Metric | Spec. |
|---|---|
| Processor Socket | Socket AM5 |
| Memory Support | DDR5, up to 256 GB |
| M.2 Slots | 3 (1x PCIe 5.0, 2x PCIe 4.0) |
| USB Ports | 6x USB 3.2/3.1, 4x USB 2.0 |
| Network | 2.5 Gb Ethernet |
Corporate Stable Model for Business Confidence
The ASUS Corporate Stable Model (CSM) program ensures this motherboard is built for longevity, offering up to 36 months of lifecycle support with 6 months’ notice before end-of-life. This makes it ideal for IT departments and businesses planning long-term deployments without frequent hardware refreshes. Each purchase includes ASUS Control Center Express, a server-grade IT management tool that simplifies endpoint monitoring, remote maintenance, and security configuration across corporate networks.
Advanced Power Delivery for Stable Performance
Featuring an 8+2+1 phase digital power design with discrete MOSFETs, the PRIME B850M-A-CSM delivers clean, efficient power to AMD Ryzen processors. The multi-layered PCB and Digi+ VRM module work together to reduce voltage ripple and heat around the voltage regulators, improving stability and providing headroom for mild overclocking. This design ensures consistent performance during demanding workloads and everyday use.
Enhanced DDR5 Memory and Storage Performance
This motherboard supports DDR5 memory up to 8000 MHz, with dual-channel architecture and a maximum capacity of 256 GB. For users without AMD EXPO™ kits, ASUS Enhanced Memory Profile (AEMP) automatically detects and optimises memory settings for better performance. Storage is equally impressive, with three M.2 slots offering up to 128 Gbps via PCIe 5.0 and two additional PCIe 4.0 slots, enabling rapid boot and load times for OS and applications.
Smart Cooling for Demanding Workloads
The PRIME B850M-A-CSM includes multiple onboard heatsinks and three chassis fan headers to maintain optimal temperatures under load. ASUS Fan Xpert 2+ software provides precise fan control, with Auto-Tuning for automatic configuration and Extreme Quiet mode for silent operation during light tasks. The motherboard also supports ASUS AIO coolers for enhanced thermal performance and quieter operation.
Versatile Connectivity for Modern Builds
Connectivity is comprehensive, with support for PCIe 5.0 graphics cards, a Realtek 2.5 Gb Ethernet port for fast, reliable networking, and a front-panel USB 5Gbps Type-C® connector for quick data transfers. The rear I/O includes multiple USB ports, HDMI 2.1, DisplayPort 1.4, and 7.1-channel HD audio, ensuring compatibility with a wide range of peripherals and displays.
Customization and DIY-Friendly Features
ASUS has included several EZ PC DIY features to simplify building and maintenance. The pre-mounted I/O shield protects ports and speeds up assembly, while BIOS FlashBack™ allows firmware updates without a CPU or memory installed. The Q-LED Core display helps troubleshoot POST issues with colour-coded indicators, and three addressable Gen 2 RGB headers let you personalise your system’s lighting with Aura Sync compatibility.
Package contents
- ASUS PRIME B850M-A-CSM motherboard
- SATA cables
- Screws
- User manual and warranty documents
Things to check first
- Confirm your AMD Ryzen processor is compatible with Socket AM5.
- Verify your DDR5 memory kit supports the motherboard’s speed and capacity limits.
- Ensure your case has the correct micro ATX mounting points and clearance.
- Check if you need Wi-Fi (this model does not include wireless connectivity).
Frequently Asked Questions
What processors are supported by the ASUS PRIME B850M-A-CSM?
How many M.2 slots are available and what speeds do they support?
Does this motherboard support Wi-Fi?
What is the maximum memory capacity and speed?
Is this motherboard suitable for business use?
Our verdict
The ASUS PRIME B850M-A-CSM is an excellent choice for users and businesses seeking a reliable, feature-rich micro ATX motherboard for AMD Ryzen processors. Its combination of stable power delivery, advanced memory and storage support, and comprehensive connectivity makes it suitable for both professional and enthusiast builds. Covered by the applicable manufacturer warranty.
| Front panel connector | Yes |
|---|---|
| 12V power connector | Yes |
| USB 2.0 connectors | 2 |
| USB 3.2 Gen 1 3.1 Gen 1 connectors | 2 |
| TPM connector | Yes |
| S/PDIF out connector | Yes |
| Peripheral Molex power connectors 4-pin | 1 |
| Number of SATA III connectors | 4 |
| Number of COM connectors | 1 |
| Number of chassis fan connectors | 3 |
| Front panel audio connector | Yes |
| EPS power connector 8-pin | Yes |
| CPU fan connector | Yes |
| Chassis intrusion connector | Yes |
| ATX Power connector 24-pin | Yes |
| RGB LED pin header | Yes |
| Number of CPU fan connectors | 1 |
| Number of EPS power connectors 8-pin | 1 |
| Number of RGB LED pin headers | 3 |
| Processor manufacturer | AMD |
| Compatible processor series | AMD Ryzen 7000 Series, AMD Ryzen 8000 Series, AMD Ryzen 9000 Series |
| Processor socket | Socket AM5 |
| Number of memory slots | 4 |
| Memory slots type | DIMM |
| Memory channels | Dual-channel |
| Maximum internal memory | 256 GB |
| Unbuffered memory | Yes |
| Supported memory clock speed max | 8000 MHz |
| ECC сompatibility | ECC & Non-ECC |
| Maximum internal memory per slot | 64 GB |
| Number of HDDs supported | 4 |
| Supported storage drive types | HDD & SSD |
| Supported storage drive interfaces | PCI Express 4.0, PCI Express 5.0 |
| RAID levels | 1, 5, 10 |
| Number of storage drives supported | 7 |
| RAID support | Yes |
| Parallel processing technology support | Not supported |
| USB 3.2 Gen 1 3.1 Gen 1 Type-A ports quantity | 2 |
| USB 3.2 Gen 2 3.1 Gen 2 Type-A ports quantity | 2 |
| DisplayPort version | 1.4 |
| USB 2.0 ports quantity | 4 |
| Microphone in | Yes |
| Headphone outputs | 1 |
| HDMI ports quantity | 1 |
| Ethernet LAN RJ-45 ports | 1 |
| DisplayPorts quantity | 2 |
| Line-in | Yes |
| Motherboard chipset family | AMD |
| Supported processor sockets | Socket AM5 |
| Cooling type | Passive |
| Audio output channels | 7.1 channels |
| Component for | PC |
| Product colour | Grey |
| Number of M.2 M slots | 3 |
| PCI Express x16 Gen 4.x slots | 2 |
| PCI Express x16 Gen 5.x slots | 1 |
| 1st M.2 largest key size | 2280 |
| 1st M.2 highest PCI Express generation | 5.0 |
| 2nd M.2 largest key size | 2280 |
| 2nd M.2 highest PCI Express generation | 4.0 |
| 3rd M.2 largest key size | 2280 |
| 3rd M.2 highest PCI Express generation | 4.0 |
| 4th M.2 largest key size | 2280 |
| 4th M.2 highest PCI Express generation | 4.0 |
| BIOS type | UEFI AMI |
| BIOS memory size | 256 Mbit |
| Power source type | ATX |
| Maximum resolution | 7680 x 4320 pixels |
| Windows operating systems supported | Windows 10 x64, Windows 11 |
| Width | 244 mm |
| Depth | 244 mm |
| Cables included | SATA |
| Screws included | Yes |
| Package width | 275 mm |
| Package depth | 275 mm |
| Package height | 67.5 mm |
| Package weight | 1.45 kg |
| Distributor SKUs | MBD-90MB1LQ0-M0EAYC, 11808588, 571022, STD10225169, CL90MB1LQ0-M0EAYC |
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