The cpu and mobo seems fine...
the thing to do :
stick just one ram and set it to 1866 see if it boot?
if it boot try run extended memtest for about 2-3 cycles... if it show no error try the other stick...
if both are fine, then need to check each slot if there a damaged slot (by try insert 1 ram and boot, try another slot,...)
slot combination 1-3, and 2-4 see if it work...
the last thing if it still don't work/no failure detected I would try update the mobo BIOS..
(it risky, but it also bring some fix & improvement)
This a long process in testing........... and if it don't work there a problems else where...