Should I add extra fans to my Antec Flux Pro Noctua Edition?

In particular, there are two possible upgrade paths that can be worth exploring if you prioritise lower temperatures over maximum quietness of operation: 

1. Adding a third NF-A12x25 G2 fan on top of the PSU shroud, blowing up towards the GPU, can help further reduce GPU temperatures, especially with large, very power-hungry GPUs such as overclocked GeForce RTX 5090 models. With less power-hungry GPUs such as GeForce RTX 5080 or non-overclocked GeForce RTX 5090 cards, we saw little to no thermal benefit from adding a third fan on top of the PSU shroud. 
2. Adding two extra NF-A14x25 G2 fans (an Sx2-PP set is preferred) at the top of the case, either both as exhaust or in a mixed configuration (an example of the mixed configuration) where the top rear fan is set to exhaust and the top front fan (right above the intake of the CPU cooler) is set to intake with an NA-IS1-14 intake spacer. This configuration can help to reduce CPU temperatures with very power-hungry (>250W) CPUs. When going for the mixed configuration, we strongly recommend using an NA-IS1-14 intake spacer on the intake fan to reduce intake turbulence noise as much as possible. 

While our tests have shown that these two measures can be helpful to further reduce GPU and CPU temperatures with particularly power-hungry systems, they also increased noise levels and therefore didn’t result in an overall improvement from a noise-normalised perspective. This is why we only recommend adding additional fans to the Antec Flux Pro Noctua Edition if you prioritise lower temperatures over quietness of operation.