Question New Ryzen 5600X system turns off and on unexpectedly ?

Jan 12, 2021
New PC Specs
CPU: AMD Ryzen 5600x cooled with a Noctua U12A, have not set a overclock
GPU: Inno3d GTX 1080 x2 8GB (From Old PC, have not set a overclock)
MOBO: AsRock B550M Steel Legend BIOS ver: 1.20 (Supports Ryzen 5000 series)
PSU: SilverStone 750W Strider Gold S, V3, 80 Plus Gold (Bought new)
RAM: Crucial Ballistix Gaming Memory, 2x8GB DDR4 3200MT/s CL16, RGB - I have this set in the BIOS at 3200mhz.
Storage: WD Green 3D NAND 240GB M.2 (Sata) SSD - Used as Boot Drive, it is new, 2xSSDs, 1 Samsung 500GB and 1 ADATA 960GB, used to store games from Old PC
Fans: Exhaust 3x Noctua, Intake 2x Noctua
Case: In Win 101, PSU is located on top.

This is my first AMD PC, am I missing something?

I built this PC on the 17th of December, 2020. Played it on that day and went on holiday till the 8th of January, 2021. The PC and everything else was unplugged from the wall throughout the holiday.
I came back to the PC, and played 1 Dota 2 game and all was fine.
The next day when watching Netflix with my partner on the PC, it turned off suddenly, and booted up to the Win10 Log In screen. After this, I thought nothing of it and logged into my PC, started up Chrome again to resume watching Netflix, when it did it again. Frustrated, I just left the PC on for a bit. I came back later that day to play another Game of Dota 2 and some Crusader Kings 3 and it did not turn off. When my partner played Cities: Skylines for a bit, it did not turn itself off.

Then, yesterday, after playing a Dota 2 game and then watching some Netflix, it turned off again. Left it alone for a few hours and came back to it. Played another Dota 2 game fine, then wanted to try the game Spellbreak and it turned off after finishing the tutorial (~15mins).

When I say it turns off, the screens go to black, then the PC turns on like if I pressed the on button. This PC case does not have a reset switch, so I do not think it would be accidently be triggered.

I then tried some fixes.
Fresh Install of the GPU drivers. Still turned off and on.
Turned off automatic restart. Still turned off and on.
After trying to run Spellbreak and few times, I wanted to see if the PSU was overheating, however it was not hot to touch.
Windows 10 is updated to the most recent version.

Fixes still to try
Check Event Logger for Errors
Fresh install of AMD Chipset Drivers
Removal of AsRock RGB Controller (Installed the beta version when I returned from holidays)
Reset the CMOS
Update BIOS to most recent version (1.80 on my Mobo)
Hey there,

Typically, random restarts like that point to a PSU issue. Your new PSU, although a pretty good one, may have issues (even new). Have you another PSU you can swap out with and test? Alternatively, if you can bring to local repair store, they can swap and test PSU for about €£$20.