So my loop goes as follows. Starting at the Corsair Pump/Reservoir combo which has the temp sensor inside it connected to the Core XT.
Then, it has a tube going to the GPU (non Corsair block), out of the GPU, into the CPU (non-corsair block), out of the CPU, into a 360mm radiator with 3 fans (plugged into the Core XT) then into a 240mm rad with 2 fans (also plugged into the Core XT) and finally back to the pump/reservoir.
The fan curve I have is aggressive, essentially turning the fans at 100% once I get to 35c just to keep things cool early for heavy games.
Yesterday I think I saw the coolant get to 69c and the fans didn't turn on at all so I restarted iCUE (or started it but it should have been running already since it's starting with boot).
I haven't seen a hardware mode on the Core XT to set a backup fan curve. The core Xt even sometimes disappears which requires a restart.
To add more, I'm on an AM5 platform with an Asus motherboard 670-E Prime.