The Phanteks G400A is the objective winner of this comparison, securing victories in five out of eight evaluated categories. Its most significant advantage over the competition is the inclusion of fans, which provides a 300% improvement in that specific area. This superior cooling configuration establishes the Phanteks G400A as the more robust option for users prioritizing out-of-the-box airflow and thermal management capabilities compared to the alternative.

Users who prioritize cooling performance and immediate system readiness should choose the Phanteks G400A for its substantial fan advantage. Conversely, the Thermaltake S100 TG is the better selection for builders who require additional storage capacity, as it offers a 50% advantage in 2.5" drive bays. Selecting between these two cases depends entirely on whether your build requires a higher volume of pre-installed cooling hardware or increased space for mounting solid-state drives.