The NZXT C1500 Platinum is the objective winner of this comparison, securing more individual specification victories than its competitor. Its most impactful advantage is a 25% higher wattage capacity, providing significantly more power overhead for demanding systems. While the Corsair RM1200x SHIFT falls short in total spec wins, it maintains a notable edge in affordability, offering a 32% better MSRP that makes it the more economical choice for users who do not require the higher power ceiling.

Choose the NZXT C1500 Platinum if your build requires maximum wattage to support high-end components that exceed the capabilities of lower-capacity units. Conversely, select the Corsair RM1200x SHIFT if you want to prioritize cost savings while still obtaining a reliable power supply. The decision rests on whether your specific hardware configuration necessitates the additional power headroom provided by the former or if the budget-friendly pricing of the latter better suits your overall system requirements.