I'm planning to build a system around a Ryzen 9 9850X3D and need help choosing a motherboard. I'm considering B850, X870, and X870E models, but the different Wi-Fi and gaming variants—and their price differences—are making the choice confusing. My budget is £200–£300, and I'd like the board to remain useful for several years without needing an upgrade. It must support a PCIe 5.0 graphics card, a PCIe 5.0 NVMe drive, BIOS Flashback, and the 9850X3D. I also want to avoid losing graphics-card bandwidth when additional M.2 or expansion slots are used. I currently have a Z790 Tomahawk Max WiFi, so I'd prefer not to downgrade in features or build quality.
1 Answer
X870 boards are required to include USB4 and a PCIe 5.0 x16 slot, while B850 boards make USB4 optional. For your budget, a good B850 can still meet the important requirements: PCIe 5.0 support for the GPU and first NVMe slot. The main thing to check is lane sharing rather than the chipset name. On AM5, the CPU normally provides 16 lanes for the graphics slot and four for the primary M.2 slot, but some boards reduce the GPU slot to x8 when another M.2 or expansion slot is populated. Check the motherboard manual’s PCIe lane diagram before buying, especially if you want to add more drives later.
Are there particular boards in this price range that support BIOS Flashback, work with the 9850X3D, and keep the graphics slot at full bandwidth even when additional storage is installed?