The Phanteks G400A is the objective winner of this comparison, securing more category wins than the Corsair 4000D RS Frame. The most impactful advantage provided by the Phanteks G400A is its superior configuration of included fans, which offers a 33% improvement over the alternative. While both cases share several identical specifications, the Phanteks G400A provides a more complete cooling solution out of the box compared to the Corsair 4000D RS Frame.

Users who prioritize out-of-the-box cooling performance should choose the Phanteks G400A to take advantage of the superior fan inclusion. Conversely, the Corsair 4000D RS Frame remains a viable option for builders who do not require the specific fan configuration provided by the Phanteks G400A. Since both cases are tied across the majority of their measured specifications, the decision rests primarily on whether the included fan advantage is necessary for your specific build requirements.