I've been experiencing the same thing im my system. After some investigation I guess that my RAM ain't 100% compatible with it. When using another sets of sticks I handnt experienced the same issue, PC ran fine for more than 10 hours in idle, not one freeze in 2 days.
I'm running on Hyperx RAM sticks.
In the compatibility list found in the Gigabyte website:
https://download.gigabyte.com/FileList/Memory/mb_memory_b450-aorus-pro-m_pinnacle.pdf
If you search for the part number you cannot find them in the list. I guess that has some to do with the timing of the RAMs, I can be wrong.