No they're not compatible. The i5 4690k is lga1150, the x99 platform is socket 2011 v3 with ddr4 support (i7's). Some i7's are 2011 v3, others (limited to quad core with hyperthreading) are socket 1150 same as the i5 4690k. Currently the socket 1150 motherboards only support ddr3 and as far as I know the only ddr4 support is x99. You'd use something like an h81/h97/z87/z97 with the 4690k.