There have been several AMD Threads in the past 6 months where 5000 series processor were overheating using MSI AIO CPU Coolers.
Most needed to RMA the MSI CPU Cooler and replace it to get proper cooling on the AMD 5000 series processors.
First thing I would do is install a inexpensive high rated TDR (At or above 150 watts) AIR CPU Cooler and see if the processor stops overheating.
If it does I suggest you RMA your MSI AIO CPU Cooler.
Or make sure the MSI AIO CPU Cooler pump is actually pumping liquid through the tubing, that it is installed correctly and is making a tight even pressure on the processor. The fan is working at full speed when it overheats, etc.
The last couple of threads the pump was showing to be working when in reality it wasn't pumping correctly thus causing the AMD processor to overheat quickly or within a very light load.
NOTE: The Maximum Operating Temperature of your processor is 95c with a TDR rating of 65 Watts. So with a AIO Liquid Cooler temperature shouldn't rise above 80c on your processor.
EDIT: There is a recall on your MSI MAG CORELIQUID CPU COOLER. See if you have one of the defective one from this article: https://www.pcgamesn.com/msi/recall-240r-360r-liquid-coolers
