does the intel core i7 4790 support ddr3 or ddr4?

It supports DDR3. Plus there's the fact that DDR4 won't even fit in a DDR3 DIMM slot on a MOBO so you'll be forced to use DDR3 anyway.

It supports DDR3 1333MHz and 1600MHz. This doesn't mean you can't use faster memory, but taking advantage of faster memory would require overclocking. I would recommend 1600MHz if you're not going to overclock, or 1866MHz if you are going to overclock. Also, the 4790k does not support buffered, registered or ECC memery. Just regular DDR3.