little explanation:
this motherboard has connections for the monitor as well, which might be disabled in BIOS and therfore only the GPU would display an image
a VGA connection is not supported by your new GPU, it only has digital outputs
a 2nd gen CPU has only PCIe2.0 and could be incompatible with your PCIe3.0 GPU
an older BIOS version of the motherboard could be incompatible to newer hardware
only the black PCIe is recommended if using a one graphics card
without the proper power connection, it might not post
another thing to try:
reset the BIOS of the motherboard by jumper