Unfortunately new ram can be defective.
It is found by testing the memory.
A significant portion of the memory testing can be done while you are sleeping or away from the computer.
Plan to start running it in the evening or when you will be away from the computer for a day.

Are you able to test the GPU for longer than 1 minute? Can you run it for 30 minutes without temperature or image problems?
FurMark - GPU Stress Test Windows 10 Performance Maintenance Tutorials