troubleshoot Pc restarts randomly

[TraflgarRa7]

Hi guys i have a weird one here. My friend's pc randomly turns off with no error or anything the screen just turns off and the pc sometime restart but most of the times the screen goes black with no picture whatsoever but the fans are spinning and the Mb lights are on but there is no picture whatsoever and i have to disconnect the powercord and wait a few minutes and then turn it on again. 
I ran memtest86 and there were no errors in all 4 passes of the test. 

Also yesterday i have been running intel burn test and heaven benchmark just to see what was the problem and it happened twice and i had to disconnect the power cord l, but today i have been running both Intel burn test and heaven benchmark and its been over 3 hours and the PC is fine and the temps are okay for the GPU and CPU.

 

Im running out of ideas and i would like to know What more tests can i do to know the problem? Can it be a bad PSU or a bad MB? 
Thank you for your help 

Note: i have noticed that even that Windows 10 installed on the SSD it takes around 5 mins for windows to boot which is really SLOWW and really weird

 

 

Pc specs 
CPU : ryzen 2600 with stock cooler
Ram: Corsair vengeance 1x8 gb
GPU: GTX 1030
PSU: Thermaltake 500w
SSD: Crucial 240gb
HDD: WD blue 1 tb 
MB: Gigabyte B450M DS3H

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3 minutes ago, TraflgarRa7 said:

randomly turns off

Could be anything.

Had the same problem.

I changed out my GPU, CPU, RAM, PSU, finally found it was the NZXT led controller.

NZXT is pretty but not too smart.

[TraflgarRa7]

Just now, 01101000 01100101 01111001 said:

Could be anything.

Had the same problem.

I changed out my GPU, CPU, RAM, PSU, finally found it was the NZXT led controller.

NZXT is pretty but not too smart.

Should i just change everything one by one and test again then? 

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1 minute ago, TraflgarRa7 said:

change everything one by one

Yes, that is basic trouble-shooting, one change then monitor rinse and repeat.

[BlazerBuddy]

@TraflgarRa7 Have you overclocked anything??

[TraflgarRa7]

27 minutes ago, 01101000 01100101 01111001 said:

Yes, that is basic trouble-shooting, one change then monitor rinse and repeat.

Hmmmm but what should i change first ive been running stress tests for 5 hours now and it didn't turn off at all.

any suggestions? 

[TraflgarRa7]

26 minutes ago, BlazerBuddy said:

@TraflgarRa7 Have you overclocked anything??

No everything is stock