Looks good only thing I would suggest is more ssd space for the encoding but otherwise good choices.
Memory is DDR4, 4x4GB, yes? Just checking.
Do you really need it though or is it just a upgrade itch? A 2600k at 4.8Ghz is still a extremely capable cpu.
Quick question on psu.
Are the EVGA SuperNOVA 850 G2 any good or am I best off sticking with Corsair?
The EVGA G2 is very good. You get a 10 year warranty after you register it.