4790 and 4790k are NOT Haswell. They are Haswell refresh. They were not supported by the original BIOS versions on B85, H97 and Z97 motherboards in many cases, especially on Intel and other OEM boards. If the CPU is not on the CPU support list but you know that it was compatible that socket on similar boards, you can always TRY it, but don't hold your breath. There are CPU support lists, for a reason.
This is no different than the recent Coffee lake and Coffee lake refresh generations. Many boards would not support, or would not support CORRECTLY and without problems, the newer 9th generation CPUs on the Z370 and other 8th generation chipsets without a BIOS update that supported them properly.