My pc sometimes goes into a deathloop

Hello everyone! Recently i had a problem where my PC sometimes starts stuttering for 3-10Secs before eventually it crashes and then it gets stuck on an infinite deathloop until i either shut down the power or it restarts 3 times into the automatic diagnostic.

First i assumed it was an overheating CPU causing me trouble so i bought a better cooler and my temps were WAY better and more stable but it didn't work. I tested my RAM sticks on memtest86 with both on and one at a time but the test showed everything is stable and no errors detected thankfully. I also for a while noticed the PC mainly crashing under heavy load (i was playing RUST with discord, chrome, spotify.. all open), sometimes under moderate load and even under almost no load (few tabs of chrome) but this happened only once.

For me i think the main suspects are either my PSU starting to fail under pressure (i'll be honest due to a tight budget at the time i bought some cheap MSI model, that was year and a half ago) or windows being windows or my RAM is no longer enough to cover whati use the pc for.

Was wondering if this happened to anyone and if there is any way i could solve this problem.

Cheers !

my specs

Ryzen 7 5700x

16GB of RAM

RTX 4060