pc shuts down random

[lukas.bockstal]

i build a new system a few months ago, since a month or so i am getting random shut downs.
my screen turns black and fans start spinning at 100%.
its not specific when playing games, mostly it happens when just in desktop or when i am wathcing youtube. i already did the memtest, intel cpu diagnostics.
i have no clue what this problem can be and would like some help from you guys.
i read a lot that it could be the psu but want to be sure before buying a new one.
system:
rtx 2080 msi gaming x
asus rog maxiumus x code
i7 8700k
gskillz 16gb ddr4 3000mhz
samsung evo 970 500gb ssd
thermalteke smart rgb pro 750w psu

 

[BringerOfTea]

Id maybe blame the PSU... everything else checks out well but I find the PSUs quality a bit lacking.
So I would maybe attribute the unstable system to that unless you have any overclocks on.

"All told, the SPR-0850F-R offers good ripple suppression, fully modular cabling, and an impressive seven-year warranty. However, we believe that its efficiency is low for today's standards. In our opinion, it's better to spend a few bucks more for a better power supply"

https://www.tomshardware.co.uk/thermaltake-smart-pro-rgb-850w-psu,review-33925-11.html

 

[lukas.bockstal]

i have some light overclocks to 4.5 ghz and gpu to 1900mhz but temps are fine since it is liquid coooled so i doubt its that.
gpu is around 65° and cpu 50°

 

[BringerOfTea]

remove them and check afterwards... temps might be fine, but the power could not be entirely stable due to the fact that the motherboard have to regulate power higher to the cpu.

 

[lukas.bockstal]

okay i will i will report later if it happens again