https://www.techpowerup.com/reviews/MSI/GTX_980_Ti_Gaming/28.html
Well it looks like intense games will load it to 280W so two of those is 560W. The I7-6700K while gaming is about 75W, so that makes that 635W so far. Add in the motherboard and other minor junk you are probably looking at a power consumption around ~660W when gaming. So I'd say a quality 750W power supply would work. Since you don't overclock this makes things easy. Oh and max load of the computer should be probably around ~690W I don't expect it to go past 700W really.
There are two philosophies here: Get a good 1000W power supply or get a good 750W power supply. Some people like to go for the 1000W power supply but it costs more. Remember, a great 750W power supply may be better than an average 1000W power supply.