gui – Ubuntu 20.04 Crashes

I recently bought a pc. After installing ubuntu it constantly crashes after about 1 hour.
The screen remains frozen. Sometimes pc doesn’t restart or shutdown or start. Mainly the gui remains stuck. Then the pc needs to hard reset. I clean reinstalled Ubuntu again but the problem remains the same.

My PC Config:
Processor: Ryzen 3 3200G
Mobo: MSI A320M pro max
Ram: 16 GB
SSD: 120 GB
HDD: 500 GB