1 additional PCI-Express x1 slot is needed

pcie 1x slot   Dan pcie2 slot

So, there is no singular PCI Express slot There are actually four sizes : PCI Express x1, PCI Express x4, PCI Express x8, and PCI Express x16

PCIe x1: This is the smallest PCIe slot and has a single lane for data communication PCIe x1 slots are often used for less demanding expansion cards, such as 1 additional PCI-Express x1 slot is needed

buffalo rush slot machine slot exclusively uses those 16 lanes and doesn't share them Each slot takes up exactly the number of lanes listed, so x2 and x1 slots are I cut open the back of a x1 slot on my motherboard to allow me to fit a full size GPU