a good tip is:
REMOVE a1200 orginal psu ..power the busboard only with the power connectors (AT) , you supply the power trough the busboard + a1200 with 1 solution.
also is your mikronik busboard the one with memory slots on ? or is it the first model?
a tip there is ... the jumpers! , do you have the manual ? ...i might have mine still..but i gave my board away and went mediator.
cheers