The NVIDIA RTX 4090 is the objective winner of this comparison, securing victory in eleven out of fourteen measured categories. Its most significant advantage is its FP32 performance, which is 2220% better than that of the AMD RX 6400. This massive disparity in raw computational capability establishes the NVIDIA RTX 4090 as the superior component for high-end processing tasks, while the AMD RX 6400 remains limited by its hardware specifications across the majority of the evaluated fields.

Users requiring maximum computational power should choose the NVIDIA RTX 4090 to leverage its substantial lead in FP32 performance. Conversely, the AMD RX 6400 is the appropriate selection for buyers prioritizing a lower MSRP, as it holds a 90% advantage in that specific category. By weighing the extreme performance gains of the NVIDIA card against the cost efficiency of the AMD option, users can align their purchase with their primary requirement for either raw power or budget-conscious acquisition.