At GDC 2019, Epic Games showcased an amazing Unreal Engine 4 ray tracing tech demo, called Troll. According to the team, this demo was running on a single NVIDIA GeForce RTX2080Ti and showcased what developers can currently achieve with real-time ray tracing.
Source: N4G PC Epic Games showcases an amazing Unreal Engine 4 ray tracing tech demo, called "Troll"