The AMD RX 9070 XT is the objective winner of this comparison, securing victories in twelve out of fifteen measured specifications. Its most significant advantage over the AMD RX 6400 is its FP32 performance, which is 1267% higher. While the AMD RX 6400 maintains a lead in power efficiency with an 83% better TDP, the sheer scale of the performance gap in computational capability makes the AMD RX 9070 XT the superior hardware choice across the majority of metrics.

Users prioritizing raw computational power and high-end performance should select the AMD RX 9070 XT for their build. Conversely, the AMD RX 6400 is the appropriate choice for those who require a low-power solution and prioritize a superior TDP rating above all other technical specifications. By focusing on these distinct advantages, buyers can align their specific needs for either maximum processing output or optimized power consumption with the correct component.