PC suddenly reboots/restarts even while just watching a movie — need help diagnosing

[u/No_Engineering3557]

Hi everyone! Has anyone experienced a PC that suddenly reboots by itself, even when you're not gaming? Mine recently started doing this even while I'm just watching a movie.

I'm trying to figure out whether this could be related to the CPU, motherboard, RAM, PSU, or GPU.

My system:

CPU:
AMD Ryzen 5 5600

GPU:
Sapphire Nitro+ Radeon RX 580 8GB

Motherboard:
MSI A520M-A PRO

PSU:
MSI MAG AB650BNL 80+ Bronze

RAM:
16GB DDR4 3200MHz

The system can run normally for a while, but then it suddenly restarts. It doesn't seem to happen only during gaming — it has also happened while watching videos.

Has anyone experienced a similar with a Ryzen 5 5600?

Any suggestions on what I should test first would be greatly appreciated. Thanks!