You should get a 650w PSU, mostly as a "future-proofing" method, in case you have plans of upgrading. I use a 750w 80+ Gold PSU for my i7-7700k, GTX 1080, 16GB RAM, 2TB HDD, 250GB SSD and it should last me a couple of years, and I will have no issues with wattage when it comes to upgrades.
TL;DR
Get at least a 650w PSU, you won't regret it.