The Phanteks G400A is the objective winner of this comparison, securing more category victories than the Corsair 4000D Airflow. The most impactful advantage offered by the Phanteks G400A is its superior cooling configuration, as it provides 100% more included fans than the Corsair 4000D Airflow. This hardware advantage ensures that the Phanteks G400A arrives with a more complete thermal solution out of the box, whereas the Corsair 4000D Airflow requires additional investment to match that specific cooling capacity.

Users who prioritize out-of-the-box cooling performance should choose the Phanteks G400A to take advantage of the increased fan count included with the chassis. Conversely, the Corsair 4000D Airflow remains a viable option for builders who prefer to select their own cooling components or who do not require the extra fans provided by the Phanteks G400A. Both cases offer comparable features in the remaining categories, making the decision primarily dependent on your immediate need for pre-installed cooling hardware.