The NVIDIA GeForce RTX 4090D is the objective winner of this comparison, securing victories in eleven out of thirteen measured specifications. Its most significant advantage over the AMD RX 6600 is its FP32 performance, which is 724% higher. This massive lead in raw computational capability establishes the former as the superior hardware choice for users prioritizing high-end processing power and technical performance metrics across the majority of the evaluated categories.

Users who prioritize budget efficiency should select the AMD RX 6600, as it holds a 79% advantage in MSRP compared to its competitor. Conversely, those who require the extreme computational throughput offered by the NVIDIA GeForce RTX 4090D should choose that card instead. The decision rests on whether the buyer values the significant cost savings provided by the former or the substantial performance gains in FP32 operations delivered by the latter.