I take it you mean Asus Z97-K, not Z170-K?
I definitely wouldn't bother with a CPU upgrade right now since you already have 32GB DDR3 RAM. Upgrading CPU would mean you'd require DDR4 RAM, and 32GB of that will set you back $300+ currently. That means you're looking at $850 for an 8700k upgrade, maybe $700 if you downgrade to 16GB DDR4. Not worth it IMO, 4790k is still a great CPU and $700+ for an extra 2 cores is a huge waste IMO. Ryzen 5 2600X with a nice B450/X470 motherboard might be alright, but that's still $500 range with 16GB DDR4.
What monitor(s) are you currently using?
What does your system not do currently that you would like it to do, or what exactly is it not doing as well as you'd like?
What case do you have?
What specific EVGA PSU do you have? EVGA have 3 different 600W units. The best of which is pretty sub par, and the worst is total garbage so I'd probably be looking at a PSU upgrade.
What's your storage like? Adding an SSD might be a good idea, even if you already have one, unless you have like a 1TB 850 EVO.