I just got caught! PCI-Express x16 and AGP share the same form factor! They do not, however, share anything else!!!! I got caught by a PCI-E x16 slot.
I plugged a VGA card in there from an older machine and it did not work!!!! The mobo was one salvaged from another older machine so did not expect a
PCI-E x 16 slot as there was only one PCI-E x1 slot and two PCI slots. There are, apparently crossover card that will work but none that I possess.