PC turning off without warning

[Devryd]

Hi guys,

I have a wierd problem with my pc. Yesterday, it turned of without warning (not shutting down, just black screen and then a restart). This happened while running folding@home. My system: r7 3800x gtx 1070. This happened twice yesterday. I have my cpu clocked at 3.8GHz while running folding@home at 1.05V. After the crashes, I added 25mV, because I thought this might have been the problem inspite of the underclock being stable in prime95. Today it happened again. Does anybody have a suggestion what might be wrong?
It shoulnt be a thermal problem since both gpu and cpu are liquild cooled and the temps are fine (about 50°C for the cpu and about 40 for the gpu)

I also overclocked my ram from 3000Mhz to 3200MHz, but that has been stable in every application

Thanks for your help 

[HQuan]

Try to run your PC not overclocked or undervolted?

[Revioli]

Check out a tutorial for viewing WHEA errors, that might tell you if it's the cpu, and specifically which core is responsible. If not, then just turning off all overclocks and underclocks, run for a few days, if it doesn't happen, turn one of them on again etc.

[Devryd]

I would like to find the component first, which is causing the problem. And I somehow dont think its either RAM or CPU. memory OC errors are mostly bluescreens and I really doubt that my CPU oc is unstable

[Revioli]

Well if it's not the CPU or RAM, it can only really be motherboard or PSU. You can't really isolate those, outside of making absolute sure it's not the other components.