93°C is way too hot to be normal for an R5 2600. The stock air cooler that ships with your CPU should be able to manage lower temperatures than that.
Things to consider and check:
Perhaps your radiator isn't mounted optimally. Is any part of it blocked from getting proper airflow?
Are any of your fans mounted in opposing directions, running too slow, or pulling when they should be pushing, or vice versa for the radiator position in the case?
Your pump may not be primed properly and therefore not adequately circulating coolant.
Did you use enough thermal interface material between the cold block of the cooler and the CPU's integrated heat spreader?
Is the cold block incorrectly mounted and making insufficient contact with the CPU?
Are there multiple pump speeds for the Cooler Master 240? Run it on high when troubleshooting temperatures.
Are any of the coolant hoses bent tightly or kinked?
Is the system running in a high ambient temperature environment? Standard water cooling, once saturated, will never be able to perform any better than the cooling system's delta over ambient, so the higher the ambient, the higher your temps in the loop.
If you can't figure out the issues with your water cooler, I would definitely try the stock cooler that came with the CPU.