Question random shut downs

[venycz]

I have built my computer a few months ago and the computer actually works great most of the time but sometimes it just turns off and can't be turned on until I unplug the power cord for a second. That happens very irregularly it doesn't matter if the computer is under load or not I ran aida64 stress test for 2 hours and it didn't crash (prime 95, fur m mark, 3dmark, and occt didn't crush it either) i can't find any pattern.
that points out on some power supply problem but it doesn't make sense to me wattage should be enough PSU calculator says my compute needs about 550 wats my PSU have 750w, i don't think it is some safety trigger because is I learned here https://linustechtips.com/main/topic/944852-dont-buy-the-g3/?tab=comments#comment-11508023 they actually trigger too late exactly opposite to my problem. Also when it crashes the power supply can still be turned on by shorting those two pins on 20 pin connectors pointing to a faulty motherboard but if the problem was the motherboard I would probably find someone else who has this problem.
things

I tried:

• changing cmos battery
• running the computer on motherboard box to prevent shorts
• adding fan to cool the vrm.
• reseating every part and every connector

my specs:

• CPU: ryzen 5 3600 @3.60ghz
• MTB: asrock b450 steel legend (bios v 2.70)
• RAM: hyperx hx432c16pb3k2/16 (2400mhz just to rule it out as a problem)
• GPU: Sapphire Radeon PULSE RX 5700 XT
• PSU: evga 750 g3
• HDD: samsung 970 evo plus 250gb,KINGSTON SA400S37480G 480 gb, Hitachi HDS723020BLA642
• CASE: SilentiumPC Signum SG1 TG

 

[Fix_that_Glitch]

Have you gone through the computer management event viewer to see what the critical error report is?

 

[Grobe]

Unfortunately, if it turns out to be a malfunction component, there is virtually no way to tell which are responsible for shutdown.

Can you elaborate exactly the behaviour of the shutdown? Does it goes snappy, or do you have to deal with error messages telling you the system is going to shut down, or maybe something between? What about sounds?

Do you experience anything at all, seconds prior to shutdowns (ie image freeze, beeps from mainboard speaker, all fans shut down, etc. . )

 

[venycz]

Unfortunately, if it turns out to be a malfunction component, there is virtually no way to tell which are responsible for shutdown.

Can you elaborate exactly the behaviour of the shutdown? Does it goes snappy, or do you have to deal with error messages telling you the system is going to shut down, or maybe something between? What about sounds?

Do you experience anything at all, seconds prior to shutdowns (ie image freeze, beeps from mainboard speaker, all fans shut down, etc. . )

It just shuts down without any warning no errors no freezing no sounds (i don't have the motherboard speaker connected) few times I heard hard drive sounds before it crashed but I tried unplugging the hard drive but it didn't help.
I made a video with where I turn it on after the crash

View: https://www.youtube.com/watch?v=K_9VhE-GJoU&feature=youtu.be
(btw I was holding the power button because I thought I need to discharge caps to turn it on later I realize that I can just unplug it for a second )

 

[venycz]

Have you gone through the computer management event viewer to see what the critical error report is?

is that what you mean?

 

[Grobe]

If the shutdown is instantaneously, the error report cannot be saved.

From the description, it is most likely the PSU being the source. But unfortunately it cannot be completely ruled out that it cannot be the motherboard too.

 

[Fix_that_Glitch]

Is your computer plugged in to a ups or surge protector? Since you built the computer yourself I would check all wiring connections from the power source to the connection. Pull and reseat them. Use an app like Cpuid Hwmonitor and check temps and voltages for anything that looks out of whack. Unplug all external devices from usb ports. Except for keyboard and mouse. Do these one at a time and see if the problem stops. Definitely start with the wiring, and monitor app. https://www.cpuid.com/softwares/hwmonitor.html

 

[venycz]

Is your computer plugged in to a ups or surge protector? Since you built the computer yourself I would check all wiring connections from the power source to the connection. Pull and reseat them. Use an app like Cpuid Hwmonitor and check temps and voltages for anything that looks out of whack. Unplug all external devices from usb ports. Except for keyboard and mouse. Do these one at a time and see if the problem stops. Definitely start with the wiring, and monitor app. https://www.cpuid.com/softwares/hwmonitor.html

my computer was connected to a surge protector so now I plugged it to a different wall socket and without the surge protector. I disconnected everything except the main monitor keyboard mouse and speakers only thing I can do is wait if it happens again.
I don't see anything weird in cpuid but I don't have much experience with overclocking voltage etc. this is actually my first overclockable computer.

 

[venycz]

so it happened again but I found out that my friend has an unused Asus a320m-k so I borrowed it nad installed my r5 3600 and 5700xt now only wait if it happens again then its faulty power supply and if not then its faulty motherboard.