You are asking for trouble. Much better off with a second mobo.
There is a space constraint and that is the reason I chose this riser model. I have mentioned my rig config in the above comment.
try doing 2 with it see if it works.
try doing 3 with it see if it works.
try doing 4 with it see if it works.
you may get it to go to 2 which is one better.
you have a low end board and it uses an amd cpu. maybe if you ask around in reddit website someone did what you are trying to do. Are you in usa? I may have a better board for you.