Hello Roger, if you have mounted everything correctly, check again if you have tightened the screws on the socket enough and if you have connected all cables for the cpu power supply. if that doesn't work, remove the cpu and check the socket to make sure it is not defective, i.e. no pins are damaged or the gold contacts on the cpu are damaged. if you think everything looks ok, it is most likely the mainboard that is defective. hope I was able to help you a little.