Port Royal is a GPU benchmark
Port Royal is a graphics card benchmark. The test measures GPU performance with a combination of real-time ray tracing and traditional rendering techniques. Port Royal does not have a CPU test.
The scene features ray-traced reflections, shadows (ray-traced and shadow mapped), transparent surfaces with ray-traced reflections, volumetric lighting, particles, and post-processing effects. The rendering resolution is 2560 × 1440.
The main role of the CPU in the rendering process is to compose the command lists that the GPU executes. The Port Royal engine is multi-threaded and divides the work between all logical cores.
If the CPU cannot submit work to the GPU fast enough, it will be the limiting factor in the benchmark, effectively invalidating the result of the Graphics test. Port Royal requires a multi-core CPU to run at high frame rates.
The exact point at which the benchmark becomes bound by the CPU depends on the configuration of the system.