ASUS PRIME B850M-A-CSM Socket AM5 DDR5 Micro ATX Motherboard
7999 EGP
- Part Number: 90MB1LQ0-M0EAYC
- Form Factor & Socket: Micro-ATX | AMD AM5 Socket (Ryzen 9000 / 8000 / 7000 Series) | AMD B850 Chipset
- Memory & Storage: 4x DDR5 DIMM Slots (AEMP & EXPO Support) | 3x M.2 Slots (1x PCIe 5.0, 2x PCIe 4.0)
- Expansion: 1x PCIe 5.0 x16 SafeSlot | 1x PCIe 4.0 x16 (x1 mode)
- Networking & Connectivity: Wi-Fi 6E | Realtek 2.5Gb Ethernet | Front USB 5Gbps Type-C | Rear USB 10Gbps Type-C
- Key Features: 8+2+1 Phase Digital Power Design | Pre-mounted I/O Shield | BIOS FlashBack™ | Q-Antenna | Aura Sync RGB | CSM with 36-Month Lifecycle Support & Control Center Express
- Warranty: 3 Years
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ASUS PRIME B850M-A-CSM Socket AM5 DDR5 Micro ATX Motherboard
AMD B850 · AM5 · DDR5 · PCIe 5.0 · 8+2+1 Phase · WiFi 6E · 2.5Gb Ethernet
The ASUS PRIME B850M-A-CSM is a Micro ATX motherboard engineered for AMD Ryzen 9000, 8000, and 7000 series processors. Built on the AMD B850 chipset with the AM5 socket, it delivers advanced AI PC readiness, comprehensive DDR5 memory tuning, and PCIe 5.0 support for next-generation graphics and storage. Additionally, the 8+2+1 phase digital power design ensures stable, efficient power delivery, while WiFi 6E and Realtek 2.5Gb Ethernet provide ultrafast connectivity. With three M.2 slots, USB 5Gbps Type-C front panel support, and BIOS FlashBack, this motherboard is ready for business and enthusiast builds alike. Furthermore, it is backed by a 3-Year Local Warranty and belongs to ASUS’s CSM program, which guarantees 36-month stable supply.
Product Gallery
Key Features of ASUS PRIME B850M-A-CSM
8+2+1 Phase Power
Stable power delivery for AMD Ryzen
AI PC Ready
Optimized for AI workloads
WiFi 6E + 2.5Gb Ethernet
Ultrafast wireless and wired connectivity
PCIe 5.0 Support
For next-gen GPUs and NVMe SSDs
3x M.2 Slots
Up to 128 Gbps data-transfer speeds
CSM Ready
36-month stable supply program
In the Box
Everything included with your ASUS PRIME B850M-A-CSM
PRIME B850M-A-CSM
Micro ATX Motherboard · AM5
WiFi Antenna
Q-Antenna · Easy attach
SATA Cables
2x SATA 6Gbps cables
User Manual
Quick-start guide
Advanced AI PC Ready
Engineered for AMD Ryzen 9000 series processors, the ASUS PRIME B850M-A-CSM unlocks the full potential of advanced AI workloads. Moreover, it provides users and PC DIY builders with a range of performance optimizations via intuitive software and firmware features. Consequently, the motherboard is fully Advanced AI PC-ready, offering both the power and connectivity needed for demanding AI applications.
Ryzen 9000
AM5
8+2+1 Phase Digital Power Design
Featuring an 8+2+1 phase power design with discrete MOSFETs, this motherboard ensures efficient and stable power delivery for AMD processors. In addition, the six-layer PCB design enhances stability and overclocking capabilities. As a result, users enjoy steady performance even during day-to-day use.
Discrete MOSFETs
6-Layer PCB
Pro Tip: Optimize Your AM5 Build
For maximum performance, enable AMD EXPO in BIOS for optimal DDR5 speeds. Use the AI Cache Boost feature to supercharge LLM workflows. Meanwhile, the BIOS FlashBack button makes updating the BIOS simple — no CPU or memory needed. Pair with a high-quality AM5 CPU cooler for best thermal performance.
🧠 AI Cache Boost
🔄 BIOS FlashBack
Enhanced DDR5 & Storage Performance
Comprehensive memory tuning options maximize the potential of your DDR5 modules. For example, ASUS Enhanced Memory Profile (AEMP) automatically detects memory chips and provides optimized profiles. Additionally, with three M.2 slots including PCIe 5.0 support, enjoy up to 128 Gbps data-transfer speeds for quicker boot-up and app load times.
AEMP
3x M.2
Empowering Connectivity
This motherboard offers a versatile range of connectivity options. Specifically, it includes WiFi 6E technology with triple the bandwidth, Realtek 2.5Gb Ethernet for faster data transfers, and PCIe 5.0 slot support. Furthermore, an arsenal of USB ports is available, including USB 5Gbps and 10Gbps Type-C connections. Additionally, the Q-Antenna attaches quickly with a snap for easy WiFi setup.
2.5Gb Ethernet
USB Type-C
DIY Friendly — EZ PC DIY
Built with EZ PC DIY innovations, the PRIME B850M-A-CSM simplifies PC building. For example, the Q-Antenna attaches quickly with a snap. In addition, the pre-mounted I/O shield safeguards ports and simplifies installation. Meanwhile, BIOS FlashBack allows easy BIOS updates without CPU or memory, and SafeSlot ensures secure PCIe 5.0 card installation.
BIOS FlashBack
SafeSlot
Best For & Considerations
✅ Best For
- ✔ AMD Ryzen 9000/8000/7000 Series builds
- ✔ Micro ATX compact PC builds
- ✔ Business and corporate stable systems (CSM)
- ✔ AI-enabled workloads and LLM applications
- ✔ Users needing PCIe 5.0 & WiFi 6E connectivity
❌ Considerations
- ✗ Users needing ATX full-size motherboards
- ✗ Those who prefer Intel platforms (AM5 only)
- ✗ Builds requiring multiple PCIe x16 slots
- ✗ Users needing more than 4 RAM slots
Technical Specifications
Platform Compatibility
Frequently Asked Questions
🔗 Explore More at Alfrensia
🔗 Official ASUS Resources
| MODEL | |
|---|---|
| CHIPSET MANUFACTURERS | |
| CPU Socket | |
| Motherboard Chipset | |
| Motherboard Type | |
| CPU SERIES | AMD Ryzen 7000 Series & Ryzen 8000 & Ryzen 9000 Series Processors |
| Technology | |
| Memory Speed | |
| Max Memory Size | |
| Memory Slot | |
| PCI-E X16 | |
| PCI-E GEN | PCIe 4.0, PCIe 5.0 |
| PCI-E Slots (M.2) | |
| SATAIII | |
| Communication module | |
| Part Number | |
| Warranty |
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Warranty & Purchase Terms
- Warranty for this product: 3 Years (official agent warranty). Details
- Immediate replacement: if a manufacturing defect appears at any time during the warranty, the product is replaced with a new one, no repair (except products that need software work). If no replacement is available, you get a full refund with no deductions. Details
- Returns: don't need it? Return it within 30 days of purchase, as long as it is sealed, unopened and complete. Details
- Inspecting the shipment: before you accept, look at the outer packaging. If the box is badly damaged (torn, wet, crushed or the tape is open) and shows signs of damage, refuse the shipment with the courier and call us right away on 01021625421. Don't open the product box before accepting. Details
- After delivery: if you open it and find damage or missing parts inside, call us within 48 hours on 01021625421 and keep the box and photos or an unboxing video. Details
- Not covered: misuse (burning, breaking, scratching, removing the warranty sticker), operating systems, software and generic accessories. Details
- Important: keep the Alfrensia warranty sticker on the product and all box contents to benefit from the agent's warranty. Details
- Payment & delivery: cash on delivery. Cairo, Giza & Alexandria within 2–3 business days, other governorates within 3–5 business days after order confirmation. Details
- Refunds: your money is back within 2 business days of receiving the product, by InstaPay, wallet or bank transfer. Details
- Your legal rights: all your rights under Egypt's Consumer Protection Law No. 181 of 2018 stay in full; the benefits above come on top. Details
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