I had very similar issues with my nzxt AIO and a Ryzen 5900X. What annoyed me the most is that other vendors offer water temperature based fan control by defaul

I had very similar issues with my nzxt AIO and a Ryzen 5900X. What annoyed me the most is that other vendors offer water temperature based fan control by default. This makes NZXT AIOs basically unfit for modern CPUs and I don't understand why they're recommended and well reviewed. I switched to a Fractal Celsius and its default setting is to control pump and fan speed by water temp. Problem solved.