The NVIDIA GeForce RTX 5090D is the objective winner of this comparison, securing victories in eleven out of thirteen measured specifications. Its most significant advantage over the competition is its FP32 performance, which is 2844% higher than that of the alternative. While the AMD RX 6400 maintains a lead in two specific categories, the sheer scale of the performance gap in floating-point operations establishes the NVIDIA card as the superior technical option in this matchup.

Users prioritizing maximum computational power should select the NVIDIA GeForce RTX 5090D to leverage its massive advantage in FP32 performance. Conversely, the AMD RX 6400 is the appropriate choice for budget-conscious buyers, as it holds a 93% advantage in MSRP. Those who require the most capable hardware available should choose the former, while those focused strictly on the initial purchase cost will find the latter to be the more suitable component.