Using a PCIe x1 card in a PCIe x16 slot

Using a PCIe x1 card in a PCIe x16 slot x1 pcie slot Figure shows a motherboard with two x1 PCIe, two x16 PCIe, and three PCI expansion slots Notice that the PCIe x16 slot has a retention x1 slot x16 slot is the most capable slot of those and if you install an x16 supported card it works at fastest x8, x4 and x1 slots are

x1 slot Dell XPS 8700 comes with a one PCIe x4 slot on the systemboard You can refer to picture below for it

x16 slot Convert PCIe x1 slot to open ended Is there a safe way to cut the closed edge? Unfortunately, most manufacturers currently produce only this mobo has three pci-e slots physically 1x16lanes ,2x1line What i found, the x16 slot is supporting only one pcie line according to