@Graytail If you can, put both of your video cards in your new machine and you can run two render tiles at one time. That should cut render times for you. I have a Ryzen5 1600x and my cards are a GTX970 and GTX980. I unchecked progressive refinement and set my tile size to 256. My render time with both cards working was 976 seconds. With this setup I can also opt to just use the card that is not running my screen and I can do anything I want on my computer while it renders including watching a DVD or youtube videos or playing a video game.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740