Honestly if there was absolutely no performance gain in Odyssey
I suspect there was, but going from total crap to almost total crap may well not be a blatantly obvious improvement.
that RX570 is slightly better than the minimum recommended for EDO (GTX780), while his i5-3470 was definitely under the minimum recommended cpu.
Now with that card and the i7. OP is arguably at minimum specs or slightly above. Very slightly.
Frontier's specs don't have much rhyme or reason to them.
I'd have expected some modest improvement, but depending on settings the game is likely too GPU limited and VRAM capacity constrained for a CPU upgrade to matter.