More than likely you have an issue with the water cooling setup. Could need to be bled better. Or have an issues with thermal compound or mounting pressure and or consistency. Could be the orientation of the hoses to the radiator, for instance if the radiator is vertical the hoses should be at the bottom. Could be not enough air hitting the radiator so a fan problem.
There are a ton of how to videos and very likely even one for your model cooler on You Tube. I would search for one but even one that is a similar setup would be fine to watch. Should give you some good ideas on what to check.
I personally went back to air cooling as I find a good air cooler to be much cheaper and less problematic than most water setups and in many cases they are even better cooling than a lot of the cheaper water setups.
Also the support department for the company that made your AIO could be very helpful in troubleshooting where the issue is. So I would ask them for help too.