Types of PCIe Slots Explained

Yes, you can put a PCIe X16 card in a X8 slot Electrically, there is no difference between the two as they both receive the same 75 W of power

I tried the clear CMOS procedure again and that didn't fix the issue I tried a GTX 750 ti(that uses the power of the slot and not external

pcie slot sizes PCIe boards can fit into slots designed for their lane configuration or higher Plugging a x4 PCIe into a x16 slot is acceptable

pcie 4 card in pcie 3 slot I tried the clear CMOS procedure again and that didn't fix the issue I tried a GTX 750 ti(that uses the power of the slot and not external