MSI PRO B550-S — ATX Motherboard for AMD Ryzen AM4
AMD B550 · AM4ATX · 4× DDR4PCIe 4.0 x16 + M.2USB-C 10Gbps · 1G LAN
The MSI PRO B550-S is an ATX motherboard with the AMD B550 chipset for socket AM4, supporting Ryzen 5000, Ryzen 3000 and Ryzen 4000G/5000G desktop processors — a straightforward board for office, business and budget gaming PCs that need PCIe 4.0, four memory slots and two M.2 drives.
The CPU-connected PCIe 4.0 x16 slot and the first M.2 slot (PCIe 4.0 x4) give full bandwidth to a modern graphics card and NVMe SSD. Four DDR4 slots take up to 128GB, and the rear panel has 1 Gbps LAN, an HDMI output for Ryzen G-series graphics, USB 10Gbps Type-A and Type-C, and 7.1-channel audio.
Before you order: Not for Ryzen 7000/9000 (AM5) or DDR5 memory. The HDMI port only works with a Ryzen 4000G/5000G CPU that has integrated graphics; with other Ryzen CPUs you need a graphics card. No Wi-Fi or Bluetooth on board.
What's in the Box
- 1 × MSI PRO B550-S ATX motherboard
- MSI shows the bundled accessories only as a picture on its specification page — ask us if you need the exact list before ordering
What It Means in Practice
- Ryzen 5 5600 or Ryzen 7 5700X plus a PCIe 4.0 NVMe SSD on M.2_1 gives full Gen4 speed without a chipset bottleneck
- Four DDR4 slots: 2×16GB now, upgrade to 64GB later without replacing modules
- Second M.2 (PCIe 3.0 x4) shares bandwidth with the PCI_E2 slot — an NVMe drive in M.2_2 disables PCI_E2
- Six fan headers (CPU, pump/system combo, four system) and 2× ARGB + 1× RGB header for case lighting
- HDMI output is limited to 4K 30 Hz — fine for office displays, use a graphics card for 4K60
What Will Not Work
- AM5 CPUs (Ryzen 7000/8000/9000) and DDR5 memory
- Ryzen 5000/4000 mobile CPUs or Athlon models not listed by MSI — check the CPU support list
- Wi-Fi/Bluetooth — add a PCIe or USB adapter
- DisplayPort output from the board — only HDMI (4K 30 Hz) with G-series CPUs
- ECC memory: the board supports non-ECC unbuffered DDR4
Key Features
PCIe 4.0 ready
CPU PCIe 4.0 x16 for the graphics card and PCIe 4.0 x4 M.2 for NVMe.
Up to 128GB DDR4
4 DIMM slots, dual channel, A-XMP overclocking up to 4866+ MHz.
Modern rear I/O
USB 10Gbps Type-C and Type-A, 2× USB 5Gbps, 4× USB 2.0, HDMI, 1G LAN.
Business-friendly
TPM 2.0 header, COM header, Windows 10/11 64-bit support.
Technical Specifications
| Identification |
| Part Number |
7C56-098R |
| EAN / GTIN |
4711377471282 |
| Brand |
MSI |
| Model |
PRO B550-S |
| Platform |
| Socket |
AMD AM4 |
| Chipset |
AMD B550 |
| CPU support |
Ryzen 5000, Ryzen 5000 G, Ryzen 4000 G, Ryzen 3000 desktop |
| Form factor |
ATX, 243.84 × 304.8 mm |
| Memory |
| Slots |
4 × DDR4 DIMM, dual channel |
| Max capacity |
128 GB |
| Type |
Non-ECC, unbuffered |
| Overclocking |
A-XMP up to 4866+ MHz (1DPC 1R 4800+, 2DPC 2R 3600+) |
| Expansion & Storage |
| PCI_E1 |
PCIe 4.0 x16 (CPU) |
| PCI_E2 |
PCIe 3.0 x4 in x16 slot (chipset), disabled with NVMe in M.2_2 |
| PCI_E3 |
PCIe 3.0 x1 |
| M.2_1 |
PCIe 4.0 x4 / SATA (CPU), 2242–22110 |
| M.2_2 |
PCIe 3.0 x4 (chipset), 2242–2280 |
| SATA |
4 × SATA 6Gb/s |
| RAID |
SATA 0/1/10, NVMe 0/1 |
| Connectivity |
| LAN |
Realtek RTL8111H, 1 Gbps |
| Audio |
Realtek ALC897, 7.1-channel |
| Rear USB |
1× USB 10Gbps Type-C, 1× USB 10Gbps Type-A, 2× USB 5Gbps Type-A, 4× USB 2.0 |
| Video out |
1 × HDMI (4K 30 Hz, Ryzen G-series only) |
| Internal USB |
4× USB 2.0, 2× USB 5Gbps Type-A, 1× USB 5Gbps Type-C (front panel) |
| Headers |
| Fans |
1× CPU, 1× pump/system, 4× system |
| Lighting |
2× ARGB V2, 1× RGB |
| Other |
TPM 2.0, COM |
| Warranty |
| Warranty |
1-Year Warranty (Singular) |
| Manufacturer Term |
Warranty period not published by MSI — claims handled through Singular |
Frequently Asked Questions
Does it need a BIOS update for Ryzen 5000?
MSI lists Ryzen 5000 as supported; boards from older stock may ship with an earlier BIOS. Tell us the CPU and we will check before dispatch.
Can I use DDR4-3600?
Yes. With A-XMP enabled the board supports overclocked DDR4 well beyond 3600; two sticks give the best stability.
Will an NVMe in the second M.2 slow my graphics card?
No. M.2_2 shares lanes with PCI_E2, not with the main PCIe 4.0 x16 slot.
Singular Expert Insight · Buyer's Guide
The PRO B550-S is an honest AM4 board for upgrading or building on a budget: PCIe 4.0 where it matters, four RAM slots and full-size ATX. If you start from scratch and want a long upgrade path, AM5 is the better platform. See compatible
DDR4 memory and our graphics cards.
✓ Buy it if you build or upgrade a Ryzen 5000 / 5000G PC and need a reliable ATX B550 board with PCIe 4.0.
✕ Skip it if you want Wi-Fi on board, DDR5 or a future CPU upgrade path (choose AM5).
→ Also consider MSI B550 boards with Wi-Fi, or an AM5 B650 board for Ryzen 7000/9000.
Not sure it fits your setup? Send us the model of your rack, switch or device and we will check compatibility before you order.