What PCIe slots are present on the ASRock B550 Phantom Gaming 4?

The primary x16 slot runs at PCIe 4.0 x16 for your GPU. A second x16 slot drops to PCIe 3.0 x4 through the chipset, and two PCIe 3.0 x1 slots handle smaller add-on cards. It’s a practical split: Gen 4 bandwidth where it matters, Gen 3 for everything else.