You might have the same situation as myself. My AIO is USB controlled, but there is also a single wire running to the CPU fan header. This makes the CPU fan header see the speed of the pump, but it cannot be controlled by the motherboard or FanExpert (as there is only a single wire). See picture attached.
So basically, if you just have that single speed sensing wire plugged into the CPU fan header, that's the reason. A quick look will confirm.
If your fans are noisy, it won't be the CPU fan as I don't believe you have one. Pumps don't normally make much noise unless there is air in the system, so look for other fans that you can change. It might be the AIO radiator fans, in which case there might be software for your AIO which you can download?
Z690 Hero, BIOS 3401, MEI 2406.5.5.0, ME Firmware 16.1.30.2361, 7000X Case, RM1000x PSU, i9 12900K, ASUS TUF OC 3090TI, 2 x 16GB Corsair RAM @ 5200MHz, Windows 11 Pro 23H2, Corsair H150i Elite AIO, 4x Corsair RGB fans, 3x M.2 NVME drives, 2x SATA SSDs, 2x SATA HDs.