The RTX cards are not simply 10 series cards with ray trace functions bolted on, they are a new architecture. This is why poser cannot gpu render with 1600 series cards. Both the 2000 and 1600 series cards use the new Turing architecture, while the 10 series used the Pasqual architecture. Poser was not the only program that could not utilise these cards, Blender had the same problem. I believe the latest release of Blenders has now fixed this, but with the lack of interest in poser that SM showed towards the end of their ownership and Bondware just acquiring Poser, Poser is still waiting for an update.