PC has restarted during memtest86 execution without errors in the log

[Carlo]

Hello, I ran memtest86 from USB drive and the computer restarted without finishing. The log doesn’t contain any memory errors. Then, I ran it again and all was ok.
Firmware is up to date. The machine with Windows 10 shutting down unexpectedly and random without any kind of dump or blue screen.
I think it is an hardware issue but what might be causing this behavior? PSU? Motherboard? CPU? Other?

[David (PassMark)]

If the machine is randomly shutting down in both Windows and MemTest86, then it is almost definitely a hardware fault.
If you eventually got a clean run through MemTest86, then it probably isn't the RAM at fault.

Without some high end tools debugging sudden restarts is hard. It is pretty much trial and error. Do you have some spare parts to swap out PSU, MB, GPU one at a time,... ?

[Carlo]

Unfortunately I don't have spare parts to swap out my hardware. I have to find wich component cause the issue in another way.
However, I would like to describe all the attempts I have made because I can't exclude anything.

A few weeks ago I saw my pc restarting unexpectedly and randomly without any kind of dump or blue screen. The only error in event log is the Kernel Power Id 41 (63). The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.
I decided to try to understand if the problem was hardware or software.

1) I left the pc on for three days in the BIOS and it never rebooted. I thought it was a software problem. I updated everything there was to update (BIOS, drivers, windows update, etc ...) but the pc kept restarting randomly. Sometimes even 3-4 times a day. In other periods, however, once every 2-3 days.
2) I started thinking about a hardware problem when during a reboot the pc rebooted again without even getting to the windows login. So I started taking memory tests.
3) Memtest86+ restarted the pc after 3 hours
4) Memtest86 rebooted the pc after 2 hours with no errors in the log
5) I ran Memtest86 again and it completed its work without errors.
6) Now I'm running a live version of Ubuntu and the pc never rebooted.

I am very doubtful. It would seem a hardware problem but then why if I keep the pc on while being in the BIOS or in Ubuntu it does not restart? Only luck?

[David (PassMark)]

Don't know for sure. Can only speculate.
Maybe you haven't been using Ubuntu long enough for the random problem to happen. Maybe Ubuntu isn't placing the system under high enough load (e.g. you aren't using the video card hardware acceleration due to missing video card device drivers, etc..).

[Kevint77]

Unfortunately I don't have spare parts to swap out my hardware. I have to find wich component cause the issue in another way.
However, I would like to describe all the attempts I have made because I can't exclude anything.

A few weeks ago I saw my pc restarting unexpectedly and randomly without any kind of dump or blue screen. The only error in event log is the Kernel Power Id 41 (63). The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.
I decided to try to understand if the problem was hardware or software.

1) I left the pc on for three days in the BIOS and it never rebooted. I thought it was a software problem. I updated everything there was to update (BIOS, drivers, windows update, etc ...) but the pc kept restarting randomly. Sometimes even 3-4 times a day. In other periods, however, once every 2-3 days.
2) I started thinking about a hardware problem when during a reboot the pc rebooted again without even getting to the windows login. So I started taking memory tests.
3) Memtest86+ restarted the pc after 3 hours
4) Memtest86 rebooted the pc after 2 hours with no errors in the log
5) I ran Memtest86 again and it completed its work without errors.
6) Now I'm running a live version of Ubuntu and the pc never rebooted.

I am very doubtful. It would seem a hardware problem but then why if I keep the pc on while being in the BIOS or in Ubuntu it does not restart? Only luck?

Did you ever solve this problem? I'm having the identical problem. I'd send you a private message but it's not allowing me to.

[Carlo]

Yes, I solved my problem. I replaced PSU and now the pc doesn't shutting down as suddenly as before.

My motherboard has two EPS 12v connectors to provide additional power to the CPU but and my old PSU only had one EPS 12v. In the motherboard manual it says that the additional power is necessary only in case of overclock but I have never overclocked the CPU. I don't understand... but with the new PSU everything works fine.

[Kevint77]

Yes, I solved my problem. I replaced PSU and now the pc doesn't shutting down as suddenly as before.

My motherboard has two EPS 12v connectors to provide additional power to the CPU but and my old PSU only had one EPS 12v. In the motherboard manual it says that the additional power is necessary only in case of overclock but I have never overclocked the CPU. I don't understand... but with the new PSU everything works fine.

Ahh strange. I don't think this is my problem. No overclock cpu, but using a super flower 850w psu that appears to be connected properly. Thanks for replying. Glad you solved your issue