3600/B550-A Pro Crashing

[pntless]

Helping a friend with his son's newly built system. Getting accurate information has been a headache as it is a teenager being relayed through my friend to me and there have been some communication failures, but here is my best-understanding. It was built about 6 weeks ago. It worked "fine" for 2 weeks without complaint and then entered a boot/windows repair loop. At this point I was helping remotely mostly by text and talked him through getting into advanced boot options and running a system restore. That seemed to fix it and the system worked "fine" for about 2 more weeks except for a couple "restarts" though I believed these to be it going through the shutdown/startup process I now believe these were resets where it just instantly restarted and didn't get stuck.

 

Now we are up to a month in, and 2 weeks ago, from the computer being built. It, again, entered boot/windows repair/reset loop. Friend got it booted to a windows install usb, wiped both drives in case his son had gotten anything on it, and re-installed windows. I had him run some diagnostics, AIDA seemed stable for hours. Memtest was stable overnight. Again, I was told since then until yesterday that it was working "fine" except for a few "restarts." Yesterday, while the kid was in online class and writing a report, it reset and entered a loop. Friend couldn't even get it to stay booted to USB to try to run recovery tools. I went and picked up the computer.

 

It booted to desktop for me at first go, but upon launching AIDA it promptly reset. It kept resetting anytime I tried to stress it and a few times intermittently between. I started ruling things out. I've replaced/ruled out everything except the CPU and motherboard. Prime95 instantly crashes and/or resets the computer. AIDA64 FPU-stress only ran for a couple of hours for me. AIDA memory stress ran for hours. AIDA CPU stress (only that checkbox marked) resets the machine within minutes. With only stress cache selected, AIDA crashes the system in less than a minute almost every time.

 

I have also, ofc, reset bios (several times) and updated bios without change.

 

Ryzen 3600, MSI B550-A Pro. Which is bad?

 

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Full Specs

Ryzen 3600

Noctua NH-U14S (originally stock cooler, replaced when we realized during initial stress testing a few weeks ago that it was approaching 100C under those tests)

MSI B550-A Pro

2x8gb Corsair Vengeance 3200 CL16

EVGA 650w GA (I think)

Inland Professional 1tb nvme m.2

WD Black 4tb HDD

EVGA 2060 KO

Win 10 Pro 2004 (my portion, at least, of the testing has been done on a 1909-based rescue USB stick)

Fractal Define 7 Compact w/ some extra fans

 

As noted above, though, I've replaced/ruled out everything except mobo and cpu.

[Guest]

So you're asking which to warranty first? Cpu or board?

 

My vote is board. I got a 50% chance of being right, and that ain't half bad.