The Phanteks G400A is the objective winner of this comparison, securing five category wins against the single victory held by the NZXT H510 Flow. The most impactful advantage for the Phanteks G400A is its inclusion of fans, which provides a 100% improvement over the competition. While the NZXT H510 Flow offers a 50% advantage in 3.5" drive bay capacity, it fails to match the overall hardware superiority demonstrated by the Phanteks G400A across the majority of measured specifications.

Users prioritizing out-of-the-box cooling performance should select the Phanteks G400A due to its superior fan configuration. Conversely, the NZXT H510 Flow is the better choice for builders who require additional storage space, as it provides a higher number of 3.5" drive bays. By evaluating these specific hardware requirements, you can determine which case aligns with your storage needs or thermal management priorities based on these distinct structural differences.