[SOLVED] Computer started randomly rebooting

[Alpassasin]

Specs:
Msi B450 Gaming Plus Max
SAPPHIRE Radeon Rx 5700 Xt 8g Pulse Gddr6 8gb 256bit
Amd Ryzen 5 3600(with stock cooler)
2x 16gb Corsair Vengeance Lpx 3000MHz DDR4 ram
Adata XPG SX8200 Pro 512 gb SSD(boot drive)
Seagate Barracuda 2tb 7200 RPM HDD
Gigabyte G450H psu
MSI MAG241C monitor



I built this computer about 1 year ago. Was my first build. For the last month I've been having problems about my computer randomly rebooting. One day it started restarting randomly. Not installed any windows or driver updates prior. So far it randomly crashed and restarted when:

Opening a new tab in chrome
Watching YouTube videos
Joining MSTeams meetings
Typing
In the login screen of Windows
Joining Discord calls
Sharing the screen in Discord
Browsing files
Opening the therminal in Ubuntu
Idling

Screen freezes and if there is audio playing it stutters just before crashing. No graphical changes like random colors.


The computer never crashes when:

Gaming
In the motherboard BIOS menu
In the troubleshooting menu which opens when windows can't boot
Running memtest86 or Windows Memory Diagnostic

Things I tried to do:

Disabling "automatic restart"
Reinstalling Windows
Running memtest86(no errors)
Running Windows Memory Diagnostic(no errors)
Turning off A-XMP in my mobo menu
Testing with individual ram sticks
Reinstalling all my drivers
RMA ing motherboard
Creating a bootable ubuntu usb and booting into it
Disconnecting the hdd
Checking the event viewer to see if there's any info about crashes(the isn't)
Checking the stability monitor to check for any recurring event before crash(there wasn't)
Booting into safe mode
Running sfc scannow command
Running chkdksk command
Double checked the front panel connectors in case reset switch was causing an issue

Keep in mind that these crashes are not consistent(I can not do the same things that caused a restart and reliably replicate it). I never overclocked my system and crashes don't give a BSOD. Since it never crashed when gaming and when in BIOS menu I thought it was my boot drive or Windows itself so I made a bootable Ubuntu usb and booted into it. Still randomly crashes but it seems like it crashes quicker. Any directions as to what else should I try or really any kind of help is really appreciated.

 

[Alpassasin]

Turns out the problem was the PSU where it would fluctuate a lot during low loads so much that it would cut the power to the system.