Question: can pcie fit in pcie?
Answer: They work fine. So if you think you are short of PCI-e slots, you may not be. A shorter PCIe card works fine in a longer slot. On PCIe X1, X4 and X16 slots, the first 18 pins are all wired the same, so as long as the PCI-Express card fits in the PCI-Express slot, it should work.