GPU fans always on?

I have a 4080rtx vertically mounted in my computer, at the top I have a 360 AIO cooler for my CPU. When the system is idling the fans on the GPU are off, and then it will raise the temperature inside the case making the AIO working with hot air = making the CPU warmer. I have no throttling problems I just wanna know if I can make it better somehow. I have a place at the bottom at the case (with dust filter) where I can put some intakt fans, woulf that be good for the overall temperaturen? Or is it better to set a custom fan curve on the gpu so the fans would be working even when idle? Or maybe both?..