Question PC shuts down randomly

Mar 25, 2022
I encountered this problem first in December a few times, now it has happened again. My pc randomly shuts down while gaming, sometimes even while browsing. There is no error message. After a shutdown, 4 out of 10 times it will not boot again, instead the fans just spin on full performance. That's why I thought overheating to be the problem, but temps are normal.
I have a suspicion the psu is at fault, but I'm not sure.

MoBo - ASUS Prime B450 Plus
GPU - ASUS GTX 1070 8G Dual
CPU - AMD Ryzen 5 2600x with stock cooler
Fans - Cooler Master Silencio FP120 PWM (3 in total)
PSU - Cooler Master MWE 550 Gold (fully modular)
Storage - WD Blue 1TB 3.5" HDD, ASUS 860 EVO 500GB, Kingston A2000 1TB m.2
RAM - G.Skill Aegis DDR4 2x8GB 3000 MHz

The entire rig was purchased in 2019. The gpu was bought second-hand.