I would not go cf 6790 either
go cf 6850 for a little more $ better performance
cf 5850 for the same price and better performance
cf 5770 for less $ and less performance
The 6790 is not good price to performance
None of the boards being discussed have the two pcie slots. Of the intel boards I've seen that are microatx with sli there is one slot between not two so one would want blower style not open air coolers for sli / cf.