Enermax has a reputation of their AIO going bad.
Sounds like your Enermax AIO is not working properly or it isn't installed correctly or is defective.
Check to make sure the pump is running at its rated RPM speed, you can feel fluid running through the tubings, The input tube to the processor should be slightly cooler than the output tube from the processor.
The Radiator fans are running at maximum when it starts to overheat and there is no air flow obstructions to the fan and radiator.
Your Ryzen if it went over 100c shut down before it would be damaged from overheating. The Maximum Operating Temperature for your processor is 95c. Obviously once it reached 95c it started to throttle but couldn't keep the temperature at 95c or below and once the temperature reached a certain level it shut down to prevent damage.
to eliminate your Enermax AIO, I would replace it temporarily with a Air CPU Cooler rated above 65 watts TDP to see if your processor keeps overheating. Most likely it won't.
I would open a Enermax AIO Support ticket to see if your AIO needs to be RMAed or not if it is still under warranty.
