and It's pretty loud at idle.
Well, what do you expect?
Besides the 2x 120mm fans it has, AIO also has a pump, that will work at constant (max) RPM at all times, creating noise. And then there's also airflow through the rad, that creates noise as well. Also, some AIOs are prone to bubbling noise, when air gets trapped inside the pump.
All-in-all, there is no benefit using AIO over tower-type air cooler, since both are still cooled by ambient air. While AIOs have several downsides, like: cost more, are noisier and doesn't last as long (2-4 years). And if AIO leaks, it can kill your hardware.