PCIe x1 slot bus speed

What is the difference between a PCIe x1, x4, and x16 slot x1 pcie slot List of Motherboards with 3 PCI-Express x1 Slots: MSI PRO Z790-S WiFi, ASRock Z790 PG LIGHTNING, ASRock Z790 PG LightningD4, MSI PRO B660-A DDR4, x1 pcie slot Anything A pcie 4 x1 slot is a whole lot of bandwidth and could be used for any pcie card with minimal real world bottleneck GPUs would be

x16pciexp slot 1 additional PCI-Express x1 slot is needed