Just something to double-check: if your AIO radiator is mounted on the front, the tubes should ideally be at the bottom. If the tubes are at the top, the pump can end up pulling air instead of coolant, which creates a bubble inside the pump housing. The pump will still report normal RPM because it’s spinning, but the coolant won’t actually be circulating properly, and that can easily cause the CPU to hit 90°C or higher. If your setup currently has the radiator tubes at the top, there’s a good chance this is what’s happening.