To make it easier for us, please use PC partpicker and then put the link into the forum, Google PC part picker and it should come up. The 5820K, in the pc with 64gb of RAM has 6 cores, where as the 4790K only has 4 cores, so for 3D rendering I think you'd be better with the more cores. With a good cooler, the 5820K can be overclocked to the same speeds as the 4790K, so you should definitely look into overclocking. However, I'd also recommend taking a look at the new skylake platform from Intel, which is an update to the Z97 Haswell platform. While these skylake CPUs wont perform better than the 5820K, they are another option and have much more up to date features than the 6700K.