MSI Z87-G55 - not working with x1 risers in the x16 slots! Hot plug doesn't help me, but some peoples says it is
try modify pcie gen in bios
and disable everything that is not needed in bios as well
The best one I used was the MSI Z77A-GD55. It is much cheaper than the MSI Z77A-GD65 You need lbr mod to make it work.